Well, sure, there are lots of examples of "scientific revolutions," where it turned out that the scientific community had the wrong idea and then got convinced, over a long period of time, of a new idea. Thomas Kuhn's famous Structure of Scientific Revolutions is all about that. There are a few very obvious and well-known cases of this (Copernican Revolution, Darwinian Revolution, Quantum Revolution), and lots of more subtle, less-well-known cases (e.g. plate tectonics). This is, arguably, science's major claim to fame: its views on the world get refined and can often change dramatically. Typically we celebrate such shifts. But those who would oppose the status quo would "weaponize" this celebration, turn it into a source of doubt.

So I would be careful about how you pitched this. To paraphrase Carl Sagan, yes, they laughed at Galileo, but they also laughed at Bozo the Clown. At any given point there are people proposing alternative views of the world or disagreeing with the "consensus" view (what Kuhn would call the paradigm), especially people on the fringes of the scientific community. Most of these people turn out to be wrong. A few turn out to be right. While a healthy skepticism about the idea that the current state of scientific knowledge is the "final" state of knowledge is certainly validated by history, this can, if one is not careful, verge into a pretty debased and anchorless epistemology: one can get into the "I can disagree with a scientific finding if it doesn't suit what I'd like to be" frame of mind. This is not an idle or hypothetical problem; on the issues you have noted, it is extremely common. (And indeed, I have been surprised to hear my own STEM students voice ideas that science is "just" opinions and scientists are no closer to truth than anyone else — this would have been seen as postmodern nonsense only a decade ago, and today it is remarkably common, because of conditioning by a few specific, well-funded industrial lobbies.)

Historians and even (some) philosophers tend to frame the question as less, "does science get at the truth?" to "what is the best way to produce reliable knowledge about the natural world?" This is how I would perhaps frame this as well. OK, you have examples of scientific consensus being inaccurate. What do you make of that? If you decide this is going to make you wary of scientific consensus, where are you going to get your necessary knowledge about the natural world from? Because we do use knowledge about the natural world all the time, both in our personal lives (when you get sick, what should you do as a consequence?) and as political powers (is it healthy for substance X to be in our food supply?). One needs an epistemology, a theory of knowledge, if one is going to live in a world like ours. "Science doesn't always have the final story" isn't an epistemology, it's at best an opposition to a very naive epistemology ("just trust science"), but it can easily swing into an even naiver epistemology ("don't trust anyone").

Other rabbit holes: what is "scientific consensus"? Is science an output of work, a process to create the work, or a community of people? At what point should scientific interpretations compel policy changes? And separate from the scientific world, at what level of individual or collective risk is a state compelled to interfere with other domains of activity (economics, religion, lifestyle choices)? I only bring up these issues to highlight that there is not a simple answer here, and that people peddling simple answers are usually just "lobbyists" of one sort or another.

At the same time, with students I would take care not to end up in a solipsistic place, where nothing but uncertainty and doubt reigns. Because as denizens of this planet we do need to make decisions about things, despite having imperfect information. How should one act in the face of imperfect information about the natural world? That's the big question to have them think about.

One issue where the scientific consensus got it wrong was the discovery of prions by Stanley Prusiner in 1982. The idea that proteins could be an infectious vector for disease was repudiated by Prusiner's peers. One practical outcome of this incorrect consensus was the spread of mad-cow disease in the 1980's, due to a common practice of feeding cows the nervous tissue, including brains, of previously slaughtered cows.

Fifteen years later, Prusiner won the Nobel Prize for his work on prions.

Phenomena have always existed that demanded explanation before there was enough hard data available. How does the sun work? How can light get transmitted through a vacuum? How old are all those fossils in the rocks? In each case, theories were put forward- the sun was a big burning pile of stuff: light was transmitted through ether: fossils are animals that were drowned in the Flood. In these particular cases more experiments led to more data and more experiments and eventually a theory was accepted. But certainly there were plenty of scientists who were slow to give into the theory of Evolution. Louis Aggasiz, for example. And circa 1900, there were quite a number of scientists who felt that evolutionary theory implied there were inferior and superior races of humans, bolstered by poor studies like those on the Kallikaks.

But like restricteddata implies, it is important to distinguish between someone who was skeptical about the existence of ether, and someone who thought the world was flat. Though Michelson and Morley were not skeptical about ether, they ended up running an experiment to establish whether or not it existed, established that it did not, and, unhappy or not, they and other physicists eventually had to go along with that. The flat-earth people were simply not wanting to know anything new and had their fingers in their ears. As are the more recent people who are skeptical about things like vaccines, or the theory of evolution, or global warming. As they aren't researching, adding more data to the question, building their arguments: and as they are certainly not keeping open minds that they can change, it's hard to actually give them the name of skeptics. They are much more in the mold of Ignatius Loyola, who said that if he saw white, but holy scripture said it was black, he'd call it black. It's one thing to be a skeptic, another to be in denial.

An interesting article here. Basically the author argues that there have been very few cases of the scientific community getting it wrong as a whole about a major for a long period of time while there was a significant outside parties claiming it was wrong (as apposed, say, scientists clinging on to outdated theories for a bit or making some minor error). He can only find three cases one a large scale.

The first in Lysenkoism in the USSR. This fulfills many on the criteria as Lysenkoism was a new idea that gained general dominance in the USSR and replaced the much more accurate genetic theories of Mendel and remained dominant despite being obvious nonsense for year. However, it was the USSR so I'm not sure it should count. It was never taken at all seriously except by a some Soviet apologists (such as Haldane) by scientists outside the USSR.

The second example he cites is Freudian Psychology. This is more ominous as it happened without the intervention of a Stalin and dominated most of Psychology for decades. Moreover, this was not just a matter of an old idea failing to be challenged but rather a new idea rising up and replacing the older idea despite being almost entirely false. In other words one cannot make the normal plea that while the world being round and flat are both false one is a lot more false since this theory was actually less true than what came before. And its not like modern Psychology builds on Freud in the way Einstein built on Newton. It simply throws it out as far as I can see. So that seems to be an example of what your looking for. I recall reading a scientific almanac from the fifties which after describing how art is based on the repressed desire of children to play with their Faeces. It concluded by declaring that laypeople often find this difficult to accept but the reader must know that experts have established it. It rather shocked me how certain they seemed. So that seems a pretty clear example of a major scientific failure.

The third case is behaviorism is Psychology which was apparently also awful. I'm not sure how awful since I know nothing about it.

So by this it seems that major errors in large scientific models are very rare- only three in the past century. But the writer of this article is a psychiatrist and two of his examples are from psychology which makes me wonder if other fields have their own that he simply doesn't know about. Can anyone name as example as large as Freudianism in their own field or some other?