Revealing mistake: In the scene where the Terminator and the T-1000 are fighting in the corridors of The Galleria, the Terminator has fired multiple shots at the T-1000. When he gets up off the floor, the Terminator throws him into the left wall and the impact hole is already visible before he hits. (00:31:45)
Revealing mistake: At the beginning, when all the guys are running away from the explosions in the war, you see a guy getting thrown into the air, but the black kickplate that propels him into the air is clearly visible.
Revealing mistake: In the first shot of the club scene, where we see the clarinet up close, the ligature (the metal band that holds the reed in place) has been placed upside down. This would make it extremely difficult, if not, impossible for the clarinet to play a single note. So, the "clarinet player" physically could not play his instrument, even if he wanted to. (00:51:00)