Character mistake: Towards the end of the movie, when Spartan goes after Phoenix in the cryolab, he fires several rounds at him with his Beretta 92 handgun. When he reloads, he inserts a new magazine and pulls the slide back. But there was no need to cock the gun since there was already a round in the chamber, which can be seen ejecting out.
Character mistake: In the scene where John Spartan goes into the sewers, he has a conversation with a Spanish-speaking woman. At the end of their conversation the woman says "Gracias" (correct Spanish) to which Spartan replies "Prego", which is Italian. Up until that point Spartan spoke perfect Spanish. (01:23:30)