The Real Ghostbusters cartoon had a few halloween themed episodes (indeed, the whole show was halloween themed), but it actually had one primetime halloween special. The Halloween Door. This special aired on ABC during primetime in 1989, then was later repeated in syndication. Oddly, I don’t recall having ever seen this episode before. I watched the Real Ghostbusters religously both on saturday mornings and during weekday syndication, but I never saw this episode.
This episode had a custom opening, a custom titlecard, and a custom closing. It also has some unique and funny moments, including Peter finally sliming Slimer for a change, a giant demon singing & dancing through the streets, and a musical number from the Ghostbusters themselves.
The plot is about some doofus with a head that’d put the frankenstein monster to shame building a machine to stop halloween (why? I dunno, because he’s just a doofus, I guess). This breaks an ancient contract and allows the demons to run rampant in the streets.
The story is much like 30~40% of the Real Ghostbusters episodes (just how many times HAVE ghost & demons run rampant on this show anyway?), but it’s still a fun romp, and the musical numbers give it that little something special.