The Police Academy trilogy being the resounding success that it was, there really was no reason for studios to stop making them. And stop they didn't so Police Academy 4: Citizens On Patrol was released in 1987 and pretty much all the main cast returned.
Critics may not have been huge fans of Police Academy 3: Back In Training but this sequel was when they started truly getting tired of the franchise as it didn't perform as well at the box-office and it even scored a Razzie nomination. The plot is pretty much exactly the same as in the third movie so right there it's obvious the writers got lazy and a lot of the predictable jokes reflect that. Bobcat Goldthwait is back as the unintelligible Zed and good old G. W. Bailey shows up again for the first time since the original movie as Captain Harris. David Spade and Sharon Stone both get small roles that, frankly, could have easily been cut out of the film entirely. Apart from the fact it's almost completely a retread of the last movie story-wise, Citizens On Patrol's most disappointing aspect is how half-assed its approach to its characters is: love interests are introduced, familiar faces pop up briefly, new recruits are brought in but none of that goes anywhere.
What made Back In Training fun was seeing the original team train a new group of goofy cadets but here, none of the new characters stand out, apart from an older lady who does the exact same schtick as Tackleberry. There are some funny moments here and there, mostly thanks to the endearing old group but everything else is just forgettable. And if you thought that the jet-ski ending from the third movie was silly, wait till you see the hot-air balloon chase in this one! To be fair, the stunts are at least impressive here as real people literally jump from planes to planes to... balloons. The best scenes are the ones where random pranks are played on either Captain Harris or the new recruits including one where Hightower (Bubba Smith) pretends to perform a voodoo resurrection at the back of a police van. Expect cameos from the likes of Tony Hawk and Randall "Tex" Cobb.
There are admittedly some laughs in this 4th instalment in the Police Academy franchise but a rehashed premise and an underwritten script lacking in anything really clever or new makes this a tired effort that only fans should have a decent time watching.