Mojovision - S2-E11
Deliberate mistake: Some of the footage of the X-Men in action that Major Domo shows Mojo is clips from previous episodes, and even clips from the show's opening theme. (00:03:36 - 00:04:22)
Genesis (2) - September 13, 1956 - S1-E2
Deliberate mistake: When Sam ejects and lands on the ground, the closeup is a flipped shot, note the "US Air Force" is backwards on Sam's helmet. (00:19:10)