The Matrix Revolutions (2003)

Revealing mistake: In the scene where Captain Mifune is defending a bridge, alone, and commands "reload", he put the right arm of the APU straight, revealing in the background some sparks that floats independent of the action and stops for a few moments.

Revealing mistake: When Smith goes to see the Oracle and he puts two of his fingers inside her forearm, if you pay attention, there is a circle where the green effects start, they don't start from inside. (00:33:25)

The-Immortal

Revealing mistake: During the battle of the dock, just before Shara takes her second shot at the digger, she is seen from behind as her weapon is being loaded. As Zee is about to slide the rocket in, the green screen is momentarily visible through the barrel. (01:05:35)

Revealing mistake: In the subway scene, when Neo gets slammed towards the wall (and crashes into it) it's visibly Keanu's stunt double.

Revealing mistake: When Neo and Smith are fighting at the end of the film - when Smith knocks Neo into the rafters of the room they are in, you can see Neo's face, and it's obviously Keanu Reeve's stunt double. (01:44:30)

Tobin OReilly

Revealing mistake: During the fight for the dock, after the first APU calls for a reload, Kid is seen in an ammo bay right before a fellow ammo runner is being sent out. As the door opens, a sentinel attacks them and all of them react surprised, except the ammo runner and the guy standing next to him, who don't react at all.

Revealing mistake: When Neo kicks Smith through the window, if you look carefully you will see that it is a stunt double. (01:46:05)

Revealing mistake: During the scene with Deus Ex Machina, see carefully the shot when Neo says "I won't" you will see two strange horizontal lines going down; visible specially on the left side of the screen. They are visible in the trailer too.