Stargate (1994)

Revealing mistake: Right after O'Neil and Jackson are captured inside the pyramid and taken aboard the alien ship a distant shot is shown of the ship while it is opening. In the sky over the ship are depictions of three moons. Each of the three moons shown in the sky of the distant planet are actually the Earth's moon when it is full but just shown rotated slightly in different positions. (01:38:00)

Continuity mistake: The pen used in the beginning of the drawing is different from the solid blue one used in the close up shot. Also, when the camera goes back to a wide shot, the color of the drawing on the whiteboard changes from blue to black. (00:17:40 - 00:18:35)

Continuity mistake: When O'Neil activates the nuke he flips up a red protective cover and then flips the switch to the up position. Later when he attempts to deactivate it, he flips up the same red cover and flips the switch to the up position again.

Continuity mistake: When Jackson re-translates the hieroglyphics, the way he writes "Buried" changes between shots.

Sacha

Continuity mistake: RA continues to wear the necklace at the end of the movie when it was taken from him by Daniel before he left the spaceship via the transporter.

Revealing mistake: On the first night at the slaves' fortress, Daniel is eating the "chicken" and telling them how good it is. After that they take him away to give him a wash. As they walk off, they pass the small fire the slaves have made. If you look at the fire closely, there is a metal circle at the bottom and the fire is coming out of seven holes in it, which means that it is a prop gas fire.

Revealing mistake: When James Spader is first exiting the pyramid after he first arrives on the planet, he begins to touch the wall on the left as the moves out the doorway. He appears to be using the wall for balance. During the last shot before he walks completely out into the open, the "solid rock" wall bends inward like it's made of rubber.