The Simpsons: Every Crossover Episode Ranked - From Worst To Best
7. 24
The Simpsons' crossover with FOX's 24, entitled 24 Minutes, is another non-canon, quasi-official crossover that would be simple parody were it not for the people involved. That said, FOX promoted this as a big deal - it was originally to be The Simpsons 400th episode, although technically (as part of an hour-long broadcast) it wound up airing as the 399th.
Featuring Kiefer Sutherland and Mary Lynn Rajskub voicing Jack Bauer and Chloe O'Brian, respectively, the plot involves an undercover bully sting, which somehow leads to a phonecall of Bart's being crossed with the "real" Jack Bauer. The entire episode is done 24-style, including the opening credits, and Lisa running a crack "Counter Truancy Unit" consisting of Milhouse, Martin, and Database.
As this really winds up being an homage with a small crossover cameo, it ranks pretty low on the overall list of Simpsons crossovers, but the episode isn't actually that bad, especially for a more recent outing.