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.
Continuity mistake: Xena leaves Darius' house, where she forgets her chakram. Then there's a shot of her riding Argo, with the chakram attached to her hip. Later Darius shows up to bring the 'missing' chakram to her.
Trivia: Karl Urban, who plays Cupid in this episode, also plays Caesar in many episodes.