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)Aidan2011
Revealing mistake: In the part in the motel where THING is doing morse code on the table to Gomez you can see the cut-out in the table where the guy's hand is sticking through the table.
Revealing mistake: Near the start of the film, when Lt. Harley is watching his love interest show off by doing gymnastics on the tree limbs, several times you can see the actual pole she is swinging on, not the tree limb. (00:08:50)
Revealing mistake: When Robin crashes through the stained glass window to save Marian and fight the sheriff, the panes of glass flutter in the breeze, revealing it to be fake glass.
Revealing mistake: When Toulon's puppet stage is set on fire, the flames in the foreground look rather like they are projected from a regularly set row of blow torches, rather than erratically flickering flames on a wooden floor. (00:25:05)
Revealing mistake: During the car smuggling scene where Van Damme is fighting on the boat one of the thugs slides/falls against the side of one of the cars. If you look closely, you can see the side view mirror on the car is made of rubber.
Revealing mistake: When Akane is sneaking out to the kitchen in order to cook something she briefly has a see-through hand, the animators haven't added any pigment and you can see the background cell perfectly.
Revealing mistake: The fire engine often shows up on the scene without any hose in the hosebed (on back of the truck).
Revealing mistake: During the night surfing scene notice that the sun is evident in the background (look closely it does not appear long). There are also shots where you can see clouds and faint blue sky. Moments later you see Keanu and Lori sitting in the water with completely different lighting which was actually taken at night and further distinguishes that the surfing shots were not actually done at night time. I heard the scene was shot during the day with a filter so it looked like it was shot at night.
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.