Fester explains he's going trick or treating at the cemetery and starts to leave. As he exits the front door, Wednesday, Pugsley and Thing follow him, but now they are wearing Halloween costumes they weren't wearing before.
When Pugsley impersonates Uncle Gustie so the kids can escape from the Puttergeist's grip, Puttergeist's blue clothes turn into a green shirt and brown pants for a couple of shots, and his brown socks turn green (the same combination he was wearing during the flashback shown earlier).