Continuity mistake: In the scene where Ace is trying to figure out the Finkle/Einhorn connection there is, what looks like, an air horn on the far end of the table to the right of the dog. A shot or two later when it shows the dog's hair around the picture of Finkle you can see the end of the horn laying right next to the dog on his left side.(This is visible in the screen shot already on the site that shows the dogs hair position changing.).
Continuity mistake: When the people take the dolphin and put it in the truck near the beginning, they close the truck door and the door is red. When it shows the truck driving away, the door is white. (00:07:15)
Factual error: The movie that Ace plays back when he goes to Finkel's house mentions that it is Superbowl 17. Only problem was the entire film references to Super bowl 19 between the Dolphins vs 49ers. Superbowl 17 was Dolphins vs Washington. Added to this the Dolphins lost by much more than just a field goal in both games.
Deliberate mistake: In the final stadium scene, the scoreboard sets forth that it is the 2nd quarter, 3rd Down and 6 yards to go. The game clock indicates that 15 minutes are left in the quarter. The announcer indicated that it was the start of the 3rd quarter, and neither team kicked off.
Other mistake: When Emilio is rummaging through Einhorn's desk drawers, he finds a note from Roger to Einhorn, thanking her for a wonderful evening, and saying that he'll see her on Friday. When Emilio calls Ace, he says that the note says that Roger was thanking her for a wonderful Saturday evening. He never wrote down what day the evening was on. It never said Saturday anywhere on the note.