Mac and Friends (partially found unaired pilot episode of animated TV series; 1990)

Mac and Friends was first pitched as a pilot or "demo" to Nick in 1990, which was rejected.

History
Mac and Friends is an American-Canadian musical comedy television series created by Harry Nebel. The show was aired twice daily as a local series on STV from May 1, 1991, to June 25, 1999.

Unlike other shows made by Harry Nebel, Theundefinedpilot wouldn't be later remade into an episode of the TV show. It seems that the characters and animation would have been very close to what would be in the final product. Still, not much else is known about it, other than the fact it was possibly going to have a different intro song and the character Professor Gunk being simply named Professor. Clips shown in promo images and sneak peeks are all that is known about this pilot.