Character mistake: When the zombies break into Buffy's house, she stakes one to check if it's a vampire. But she should know full well that it isn't a vampire as they all broke into her house without being invited.
THGhost
It's Christmas in Canada - S7-E15
Character mistake: In the first scene, the Broslofskis are lighting their hanukiyah. It is the first night, and the lone non-shamash candle is on the far left side as they look at it. However, Hanukkah candles are placed in the hanukiyah starting from the right.
DavidK93
Touchstone - S2-E14
Character mistake: The team are finding out who could have stolen the weather device from Madrona and find an energy spike at the same time SG2 are on a mission. "But SG2's mission is galaxies away from Madrona" Says Teal'c. At this time the only missions the teams could go on was in our own galaxy and couldn't be galaxies away.
Cybermoose
Character mistake: In Episode 1.11, Hank says "McDonnell Douglas L-1011" when it is really Lockheed L-1011. McDonnell Douglas produced the DC-10, which was similar.
Ghostrider1701
The Madness of King Bob - S4-E9
Character mistake: Whenever the Hustler Kid delivers Randall's prize in the beginning, he says, "Grand prize delivery for Mr. Randall C. Weemes." But Randall's middle initial is J.