In the scene where the T-1000 pries the elevator doors open, the Terminator shoots him in the face, and his head splits open. If you pause at just the right moment, you will see that the T-1000's head is already broken apart before the gun goes off.
Although this is not a slip-up, it is a funny part of this scene that's easy to miss. Watch Silverman in the back. He is standing against the wall when the shooting is happening, but at the last time the T1000 pries the door open, you can see behind him & Silverman's not there, like he fainted.