I posted this at GB Fans originally but thought I'd see what the folks here think....
Well, there are three episodes that seem to straddle the earlier and later seasons: Transylvanian Homesick Blues, The Grundel and Slimer, Is That You?
In the case of The Grundel, it could be that it was written earlier (possibly with the ABC Season 1 episodes), held over and then animated and recorded with the new voice actors. It was written by JMS, has Janine with her original personality, and is notably darker in tone than the other third season episodes. But I'm not so sure....
With Slimer, Is That You?, I guess there was an error, which lead to it being swapped in the schedules with....
....Transylvanian Homesick Blues, which has the original Janine character design, but with Kath Soucie voicing her. The rest of the episode is ambiguous-it has the rougher animation style of the syndicated episodes, but with Dave Coulier as Peter, and Slimer's new design and characterisation. The plot doesn't really fit in with the other third season episodes, though (I suspect that, under ABC's new vision for the show, vampires would have been out). The episode was in fact originally broadcast in syndication, but is listed as part of season 3 on most sites.
Then I remembered a post on the old GB.net site, in which someone remembered watching a version of Baby Spookums which had Lorenzo Music as Peter (there was another post recalling how Loathe Thy Neighbour had Music too, but I'm going to chalk this up to an error of memory).
Is this evidence that season 3 might already have started production when ABC decided to retool the show, and that JMS' decision to quit came a lot later than expected? Any ideas?
"The only edict I serve is my fist."- Garfield, "Garfield's Royal Rescue"