Dying For Pie / Imitation Krabs - S2-E6
Other mistake: Dying for Pie: When SpongeBob seems to have exploded behind the brick wall, a brick flies out of the wall. Then, when the second explosion happens, the brick reappears in the wall mid-shot, then disappears when the wall hits the floor. (00:10:20)
Dying For Pie / Imitation Krabs - S2-E6
Other mistake: Dying for Pie: Near the end, Squidward tells SpongeBob that he spent the whole day with him doing all kinds of ridiculous things because he was supposed to explode. Right when Squidward says, "explode," a small portion of his head gets cut off briefly. (00:10:52)
Dying For Pie / Imitation Krabs - S2-E6
Other mistake: Dying for Pie: When SpongeBob trips on the rock at the end, he says, "Oops," before he even trips on it. (00:11:47)
Dying For Pie / Imitation Krabs - S2-E6
Continuity mistake: Before Spongebob drops the pie in Squidward's face, the rock he tripped on was never there.
Dying For Pie / Imitation Krabs - S2-E6
Revealing mistake: In the episode "Dying For Pie", you can see Mr. Krabs' legs disappear when Squidward says, "But you can't pay me enough to act brotherly on that guy!"
Dying For Pie / Imitation Krabs - S2-E6
Continuity mistake: Mr Krabs has no eyelashes when he tells Squidward not to tell Spongebob about the bomb he ate. (00:05:01)
Dying For Pie / Imitation Krabs - S2-E6
Continuity mistake: In "Dying For Pie", Mr. Krabs takes a piece of the pie, leaving a bit of the pie missing. Later that day, Spongebob pulls the same pie out of his pocket, but the pie is fully together with no pieces removed.
Dying For Pie / Imitation Krabs - S2-E6
Continuity mistake: SpongeBob makes Squidward a tear jumper and there is a shot of Squidward sighing. In this shot, we can see no-one standing around the register. In the next shot, Mr. Krabs has suddenly appeared next to it.
Answer: I believe this is the Season 6 episode "Spongicus".