I hardly remember Seasons 14 through 16 and I've barely seen any episodes from Seasons 17 through 22, but I remain fairly confident that there's no gag in the history of the show worse than Brandine and the umbilical cord. That was like the anti-funny.
I can't shake the feeling that this episode was trying to be "22 Short Films About Springfield", but didn't have the chops to pull it off. It wasn't bad, but it wasn't good either - it just sat there, begging me to laugh at it. Every so often, a potentially good joke would come along and then fall flat on its face. For instance, Chief Wiggum being too fat to bend over ("Stuff on the ground is outside my jurisdiction") and not being able to apprehend Snake crawling between his legs could have been funny if it had stopped there...but then he has to lose his hat, and his pen, and his pants, and then his high school girlfriend has to walk by. Sorry, writers, you killed it.
All the money this show makes, I'm surprised they can't splurge on better CGI. There was a lot of it in this episode, especially on the Duff blimp, and it all looked like something out of a PlayStation 1 cutscene.
I think the only big laughs I got were from Homer sucking the frosting off Maggie's head, and Nelson making a wooden "Haw Haw" in shop class. It says a lot about the writing quality of an episode when only the sight gags make me laugh.