Yes, absolutely.
To begin with, don't forget that the romanticized Western image of samurai as hyper honor focused warrior monk types is pure exoticism with no real historic backing.
More to the point, like with the knights of Europe, while there was an official ideal of honor it was more prescriptive than descriptive and when you have a large group of heavily armed men some are going to be scumbags.
Further, "samurai" simply meant "person from the caste permitted to carry weapons", towards the end of the Tokugawa period (1600-1868) a great many samurai class men had no real weapon training, a minimal pension from the government, and generally survived by running up debts which were nullified every few years by government edict.
The Seven Samurai takes place earlier, in the Sengoku period (aka the Warring States Period), at a time of chaos and general confusion. There was no centralized government, no rule beyond what the local warlord decreed and could enforce, and samurai (again, meaning "people who carried weapons", not "super highly trained and deeply honorable warrior monk types") were thugs enforcing the will of their local warlord, which usually meant stealing whatever they could from the peasants and calling it taxes.
Or, worse, they were ronin. When a warlord was defeated his soldiers (samurai) often just wandered off and turned to banditry to survive. There's a lot of mythology and several stories involving deeply honorable ronin seeking adventure and vengeance for the people who betrayed their lords, but mostly in real life they were just armed and trained men who took whatever they could from the people least likely to fight back.
You might check out State of War, it's more about the somewhat earlier times than the Sengoku period, but most of what it covers applies to the later periods as well.
For an interesting, often funny, first hand, primary source, account of daily life for a poor man of samurai class during the mid Tokugawa period check Musui's Story, it's a very quick read, an autobiography written by Musui himself, who lived a quite disreputable life and busts a lot of myths of the noble honorable samurai.
TL;DR: even at the best of times, samurai were just soldiers, and historically soldiers weren't what you'd call very nice. In the worse times they were just bandits. The idea of samurai as super honorable warriors is just a myth.
Oh yeah, there's plenty of legitimacy to this accusation. It might even be closer to the truth.
William Wayne Farris quotes Paul Varley in describing the samurai as "extravagant, rambunctious, and lawless." Taken from Japan to 1600:
As social upstarts, samurai were "extravagant, rambunctious, and lawless." Having no sense of good breeding, they gambled and spent all their time partying, drinking, and engaging loose women. Legislation promulgated in 1336 tried to curb such behavior, but to little avail. Born in 1306, Sasaki served first the Hojo and then Go-Daigo. In 1335, he switched sides again and adhered to Takauji. For his service, he was named a daimyo, and ironically, helped to write the vey law codes that he came to flout so freely. In 1340, for example, when Sasaki was throwing one of his many parties, he and his followers admired some maple trees on an excursion, so much so that they ripped the branches off the trees. The garden happened to belong to a temple headed by the brother of a retired emperor, and his servants beat the branch gatherers. When Sasaki heard about the thrashing, he led three hundred mounted soldiers back to the temple and set it on fire. The priests demanded Sasaki's head, but the Ashikaga merely ordered him into exile. On the day when he left for distant parts, Sasaki placed three hundred members of his family and retainer band in an entourage showing off the latest in martial finery, including quivers covered in rabbit skin. They brought along quantities of sumptuous food and had courtesans waiting at every inn along the exile route. It became a pleasure excursion, not the punishment for a grave crime.
Well that's just an example of a lawless samurai (and his equally lawless samurai retainers). What about pillaging, raping, and burning?
In particular, the armies provisioning techniques inflicted considerable hardship on the populace at large. Between 1335 and 1386 there were at least seventy-one incidents of arson and harvests stolen by armies in the field. In one particularly egregious case, in Mino in 1340, samurai "attacked residences, stole the rice and other grain laid aside as seed, so that the peasants fled and there was no cultivation going on."
The above is from the Northern and Southern Courts period, but similar records exist back in the Genpei War and also the Sengoku. The term in Japanese for this kind of raiding of civilians is 乱妨取り (ranboudori) or 乱取り (randori). Japanese lords (or really, lords all over the world at this point) simply did not have the ability to fully supply their armies, especially with food, and so allowed or even commanded their men to just take it from the countryside. The warriors pillaged, raped, burnt, and sold people into slavery.
In the Sengoku, at least part of the reason for many daimyos' expeditions was to prevent hungry and restless samurai from eating the daimyos' own food and pillaging their own domain, and instead profit from doing it to others. For example:
Pillage, arson, and rape took place from one end of the archipelago to the other. In western Honshu, the Mori left behind a legacy of glory arising from an annual cycle of devestation. Their armies plundered fields during the spring planting, mowed down wheat crops and interfered with farmers during the busy summer, stole the harvest in the fall, and broke into granaries, burned peasant homes, and left their victims to freeze or starve to death in the winter. At Hineno Estate in the Kinai, soldiers repeatedly burned residences, raped women, kidnapped and pressed unsuspecting cultivators into service, and pilfered peasants'personal belongings, tools, and livestock. Just west of the Kanto, Takeda Shingen was among the most creative in profiting from the war-capturing the enemy's women, children, and disabled and offering them for sale back to their relatives. Shingen's brand of war-profiteering shattered families and undoubtedly resulted in the death of many captives, even as it fed his war machine.
Even my personal favourite Sengoku daimyo, Uesugi Kenshin, despite a reputation as one of the most honourable daimyos, did this. Fujiki Hisashi noted in 雑兵たちの戦場 中世の傭兵と奴隷狩 (The Battlefield of Common Soldiers-Mercenaries and Slavers of the Middle Ages) that Kenshin's frequent eastward campaigns turned many places in Kanto into living hell. Just goes to show that, like the knights of Europe, whatever supposed honour the samurai had did not extend to commoners.
Kuroda Nagamasa ordered screens to be painted of the Siege/Battle of Osaka in 1615. The screen depicting the aftermath of the fall of the castle shows the absolute chaos as the people tried to run and escape the absolute slaughter. Stephen Turnbull in his work on the Siege of Osaka quotes the letter of Richard Cocks:
Also we have had great troubles and wars in Japan since our arrival, which hath put us to much pains and charges in sending up and down to save our goods, and yet for all that some is lost and burned, two great cities being burned to the ground, each one of them being almost as big as London and not one house is left standing, the one called Osaka and the other Sakai; and, as is reported, above 300,000 men have lost their lives on the one part and other.
Things were so bad that many villages and commoners came together in armed groups and fortified their villages to resist. At any point they could, they got back at the samurai, finding small bands and assaulting, killing them, called 落ち武者狩り (ochimushagari). Even big names fell victim to these bands, most famously Akechi Mitsuhide getting killed on the retreat from his defeat at Yamazaki. Some villages and bands came together under the banner of Ikko buddhism, and some even grew to such sizes they kicked out the daimyos all together ruled their own domains.
The idea of Bushidō, "the way of the warrior", and its connection to chivalry, honor, etc., that is popping up in the answers to this question seems flawed. Bushidō is a relatively modern concept centuries removed from when samurai were actually involved in wars.
Bushido became a widely accepted idea in the Japanese national consciousness when a Japanese Quaker, with no background in history,named Inazō Nitobe wrote Bushido: The Soul of Japan (1899). If you read the introduction it becomes apparent that he wrote the book out of a sense of inferiority to Western society and hoped to create an idea of something inherently Japanese that is of equal standing with the west. He writes "I have tried to illustrate whatever points I have made with parallel examples from European history and literature." He then proceeds to create Bushidō by choosing stories without any historical veracity or analysis of the historical context of these stories. He then frames these stories in terms of Western philosophy and history.
You can see how flawed Inazō understanding of the history of the samurai is throughout the whole work. One of my favorite chapters is "The Sword the Soul of the Samurai" in which he declares "When Mahomet proclaimed that "the sword is the key of Heaven and of Hell." he only echoed a Japanese sentiment." Of course the problem with this is that the idea of the sword being the main weapon of the samurai only came about after the samurai had ended their wars and entered an era of relative peace during the 16th century. When samurai basically became bureaucrats they increasingly focused on idealizing the symbol of their power, the sword that they alone were allowed to carry. If you look at the first codes that Tokugawa laid down about samurai and the aristocracy, there is no mention of focusing on swords. In fact, it mentions horse riding and archery as being important parts of being a samurai.
Ancillary question: I've often heard that during some periods samurai had right of life and death over peasants and could essentially kill them for whatever cause. Was that ever true or is that an exaggeration?
Not that I think the discussion thus far has been wrong, there are two things to consider:
This is a Kurosawa film, and his filmmaking career was probably at its best imho in the 10-15 years following WWII. Some of his better known films (Rashoman in particular, but many to some degree) involve an admission that military honor was not all it was cracked up to be. The end of the war (and in particular, what had happened in China) spurred some self-criticism. This is not to suggest that the militarism of WWII were analogous to the Samurai cultures of the Edo or Warring States periods. However, the parallels are certainly there.
Also, it is worth noting that the term Ronin was essentially a Samurai that was not obeying the proper hierarchy by maintaining allegiance to a particular lord. So even though there was a Confucian-style caste system, it was not as cut and dry as one might think, you could sink to the lowest of the low while still being a samurai.
