Continuity mistake: When we first see the Hungarian guy lying in the hospital he is burned over most of his face, however his eyebrow is still there. In a later scene, his eyebrow is gone but his eyelashes are still there.
Plot hole: The premise is that the back-story is a fabrication, including the five being placed together in the police line-up and in custody in order to get them to work together. But in the flashback of Keaton in the restaurant, it is Dave Kujan who takes Keaton in. It is inconceivable that Kujan would be complicit in the staging of the line-up (and doesn't fit with the plot). And if Verbal is inventing it, then Kujan is going to know it didn't happen. It doesn't make sense and undermines the plot.
Other mistake: The burned guy who's supposed to be Hungarian keeps making bad language mistakes, although his pronunciation is great.