The Dark Phoenix (4): The Fate of the Phoenix - S3-E14
Continuity mistake: When Gambit and Storm were knocked unconscious in battle, they were lying next to each other. When Xavier revives them in order to stop Dark Phoenix, they are several feet away from each other. (00:10:54 - 00:15:15)
Chosen answer: That's from the Disney version of "Tom Sawyer" (1973). I remember that scene, watching it as a child.