The Ghost Next Door (1) - S4-E3
Deliberate mistake: Right before rising to check out who was calling her name, Hannah sets her laptop, which she was using to write a letter, on the bedspread. The computer screen is shown to be blank, meaning, 1. she switched it off, which she didn't, or 2. it was out of order, which doesn't make sense since she was using it seconds before. (00:02:10)
Answer: Whoever created the Masked Mutant comics would still be around to create other comics even with the Masked Mutant dead and the Galloping Gazelle retiring, so Skipper could still receive different comics with all new characters. When Skipper goes into the Masked Mutant's lair, he is hit with a beam of light that turns him into a comic book character so after saying that he's the Colossal Elastic Boy, he turns into the hero at the end of the episode.