Transylvanian Homesick Blues - S2-E65
Character mistake: Ray says that it's the very first time they've dealt with vampires. In Season 2 Episode 25, "No One Comes to Lupusville", the Ghostbusters had to deal with both werewolves and vampires.
Character mistake: During the radio show, the radio host gives the radio station's phone number as 555-4455, Alf then softly repeats the number back before he gets to the phone. He then picks up the headset and dials a number, but the numbers he presses on the phone don't match up to the number given by the radio station. (00:04:10)
I'll See You in Court - S5-E20
Character mistake: Charlene says Rocky was nominated for 9 Oscars, it was actually nominated for 10 but in 9 different categories.