Revelations - S5-E22
Revealing mistake: Just before Teal'c and O'Neill get to the engine room door, Carter can be seen hiding around the corner. (00:27:40)
Revealing mistake: Even after Teal'c is dead, you can see in one shot that he is still breathing.
Revealing mistake: When Jack is asking the Martian where he got the idea for the show, you can see the camera light reflected in the Martian's glasses.