When Cameron is posing as a waiter a man puts an empty glass on his silver tray. When the camera angle changes the glass is half full with brown liquid.
The Omega Speedmaster said to only be for astronauts is in fact the only watch approved by NASA for Extravehicular activity, but it can be purchased by anyone.
The cell phone Andy Faust uses to call his mother is not activated. The close-up shot of the phone after Dina rear-ends his car clearly shows the error message "Your phone did not activate. You may need to find an area with better coverage (near a window or outside)."
The video tape that they refer to throughout as a Betamax tape is actually a VHS format tape.
A prison warden has no power to offer a prisoner a plea bargain as the warden offers Jonathan.