Pre-Hibernation Week / Life of Crime - S2-E13
Continuity mistake: When Spongebob has melted from stress and exhaustion, he is trying to talk and Sandy tells him to "hold that thought", and you can see the bike that they were riding, in the background. When she makes the fly fishing joke, the bike is gone, and there is a small plane. A few shots later the plane is gone as well.
Pre-Hibernation Week / Life of Crime - S2-E13
Continuity mistake: When his pants fall off when he's trying to hide, his pants are hooked to the plant by the brown part of his pants, but when Sandy comes looking and she sees his pants on the plant, they're hooked by the white part.
Pre-Hibernation Week / Life of Crime - S2-E13
Continuity mistake: When Spongebob and Patrick have run away, when they are fighting about the chocolate, Patrick has chocolate all over his mouth. Patrick says something like "I'll get there first" and starts running after Spongebob, and in the next shot his face is completely clean.
Pre-Hibernation Week / Life of Crime - S2-E13
Continuity mistake: When Spongebob falls off the sea needle, he lands on a . It shows his ripped off skin, then it shows his back with the piece missing, but the shapes are different.
Pre-Hibernation Week / Life of Crime - S2-E13
Continuity mistake: Sandy's bikini bottom is gone as she's bending over to paint the fence.
Answer: I believe this is the Season 6 episode "Spongicus".