I have not seen the movie but I know it is supposed to be vaguely based off Ibn Fadlan's travels, which I have read the relevant parts of. You can also find a translation and commentary here by Montgomery.

The reason why I feel comfortable answering this anyway is because there is simply very little known here. We know very little about Old Norse religion. While the impression one might get from the Eddas and books derived from them on the mythology is that we know a great deal, this mythology is largely based on those very few sources, written down in Iceland by Christian authors well after the mythology was no longer believed, and centuries after the supposedly-historic events. So we don't know how well they match reality. But a more important aspect here is that the mythology and its stories is likely to have been much less important to ordinary people than practical cult and ritual; how the religion was actually practiced. On this topic the Eddas and Sagas tell us very, very little.

One thing we can rule out directly is that there's no record of any prayer in the Christian/Abrahamic-religion sense of it. That is, things like private prayer, penance and such. There is no reason to believe that was 'a thing' to the Norsemen of old. However, prayer in the basic sense of the term as a request to the gods. The point of making sacrifices was usually part of a request from the gods for intercession (and the fact that sacrifices were made is one thing we do know; both written accounts and archaeological evidence are in agreement there).

Now when it comes to Ibn Fadlan, we don't even know for sure whether he was talking about Scandinavians. He writes about the Rus - which could the actual Rus' people, the rulers of Novgorod and Kiev. Or it could mean Scandinavian, from whence the Rus' originated, and would then likely mean Swedish Varyags/Vikings. Or it could refer to Slavic people in the area which he conflated with the former. However, the more likely and generally-assumed interpretation is that they were in fact Scandinavians.

The reliability of Ibn Fadlan's account is also somewhat questionable; he does not disguise his religious biases; noting at length what he perceives as their disgusting habits and ritual uncleanliness, and these parts may be exaggerated.

Ibn Fadlan also gives the only detailed, eyewitness account of a Norse human sacrifice and burial ceremony. It's very well known but I won't get into it here as it's somewhat besides the main point. The relevant bit here is that Ibn Fadlan has the most detailed - by far - description of Norse veneration of idols and prayers for intercession from the gods. So to quote it at length from Montgomery:

The moment their boats reach this dock every one of them disembarks, carrying bread, meat, onions, milk and alcohol and goes to a tall piece of wood set up <in the ground>. This piece of wood has a face like the face of a man and is surrounded by small figurines behind which are long pieces of wood set up in the ground. <When> he reaches the large figure, he prostrates himself before it and says, "Lord, I have come from a distant land, bringing so many slave-girls <priced at> such and such per head and so many sables <priced at> such and such per pelt." He continues until he has mentioned all of the merchandise he has brought with him, then says, "And I have brought this offering," leaving what he has brought with him in front of the piece of wood, saying, "I wish you to provide me with a merchant who has many dinars and dirhams and who will buy from me whatever I want <to sell> without haggling over the price I fix."Then he departs. If he has difficulty in selling <his goods> and he has to remain too many days, he returns with a second and third offering. If his wishes prove to be impossible he brings an offering to every single one of those figurines and seeks its intercession, saying, "These are the wives, daughters and sons of our Lord." He goes up to each figurine in turn and questions it, begging its intercession and grovelling before it.

So at least in Ibn Fadlan's description, the prayers consisted little of short straightforward requests. Is it an abridgement on his part? Is it even reliable?

From archaeology, posts in the ground are a well-known feature of Old Norse cult sites (vé or ví). The physical description seems plausible. As for the idols themselves, there are multiple accounts of such 'wooden men' (trémenn). So this part of Ibn Fadlan's story seems entirely plausible. As for the other accounts:

Adam of Bremen, a contemporary but not eyewitness account wrote of the temple at (Old) Uppsala in Sweden, where there supposedly stood three idols of Thor, Oden and 'Fricco' (Frö/Freyr). Another rather poignant reference to the idols is at the end of the Saga of Ragnar Lodbrok, the figure Ogmundr the Dane runs across a giant ancient 'wood man', overgrown by moss, who speaks to the men in verses lamenting that he is no longer worshiped.

Yet another but late reference to wooden idols is in Flateyjarbók, which also has a short story Vǫlsa þáttr, about a family of pagans who keep an embalmed horse penis and pass it around reciting a verse over it. Until one day (and might be a later twist on an older story) the King-Saint Olaf of Norway comes by incognito and throws the penis to the dogs and convinces the family to convert to Christianity. The interesting thing about this story is that it depicts a private ritual and ceremony, as opposed to the few others described. (it also underscores some other known aspects of the religion like fertility cult and horses as a sacred animal) As it is described, the prayer dedicated the sacrifice to Mörnir (an otherwise unknown character, perhaps a giant). The 'gods and Gefjon' are also invoked at one point. However Flateyjarbók dates from the late 14th century and is thus 400 years after the events it purports to describe.

So these small scraps are the sum total of our knowledge of Old Norse prayers - one written by a witness who only got the text in translation and was negatively disposed, the other written very late and possibly more of a saint story about Olaf than an accurate depiction of pagans. In either case though, the words used when sacrificing or requesting from the gods appears quite simple and blunt. It's possible they originally consisted of flowery prose and were later shortened and abridged, but it's closer at hand to just assume that they were like that to begin with.

In other word, what we know about prayer in Old Norse religion is that words were spoken as part of cultic rituals with sacred objects, at cult sites but perhaps also in private. The words were not very flowery and would perhaps not look good in a movie (I suspect any prayer in the movie would be much more elaborate). If anything, these stories may illustrate a relative importance of actions over words in the cult.