Revealing mistake: When Xena 'dies', her pulse is checked, and they can't find one, yet you can see her pulse in her neck. (00:30:30)
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.
Revealing mistake: When Gabrielle is hitting her staff against the tree and screaming, if you look carefully for the last hit, the staff is bent. Most of their props were rubber with a metal rod inside them. The actress bent the metal rod because she was hitting so hard.
Revealing mistake: When Xena is explaining to Gabrielle what happened at Cirra, her native New Zealand accent can be plainly heard when Xena says "ordinary".
Beware Greeks Bearing Gifts - S1-E12
Revealing mistake: In the beginning battle, as the Trojans fight from the top of the gates of the city, one falls off. The entire Stone Wall shakes when he hits it.
Is There A Doctor in the House? - S1-E24
Revealing mistake: After Gabrielle's been wounded, there's a scene where she starts thrashing violently. A little after that, Hippocrates declares her dead despite the fact that you can see her breathing in the previous shot.
Revealing mistake: When Marcus is hanging off a wall in Hell and under attack from a harpy, there's a shot of Xena jumping on said wall to help him. When she lands, you can see the pavement give in a little, like it's made of rubber instead of stone. (00:35:45)
Revealing mistake: When Xena is fighting Celano, right after he grabs his knife to try and kill her, the shot changes to Xena, who after dropping back to the ground is supposed to be unsheathing her sword, but actually has it out already and just pretends to. (00:39:00)