Revealing mistake: When Hope and Gabrielle are talking, and Gabby says she's sorry the poison didn't kill Hope, look when the camera is on Hope and behind Gabby. Since Renee O'Conner plays both parts, a double is used from the back. The double is really bad. Her build is way too small and un-muscular to be Gabby.
Xena: Warrior Princess (1995)
1 revealing mistake in Sacrifice (2) - chronological order
Beware Greeks Bearing Gifts - S1-E12
Revealing mistake: At the end when Xena is fighting Deiphobus, he pushes her up against a large rock, every time she hits the rock it moves, as if it were foam.
Trivia: This was the 2nd of a two part episode, and the script had to be totally re-written as a mostly Xena Free episode due to Lucy breaking her pelvis in an accident on the Jay Leno show.