I think you are thinking of the same film nada just asked about. It's called "Twice Upon a Time," and it was produced by George Lucas in 1983. See my response to nada's "Sidekick called "Mom"" thread.
Here's the IMDB link for the movie. Gee! Years and years without any interest in this one, and two people ask about it within 24 hours of each other! Cool. If I'm right, that is.
No idea on this one..... so here's a shot in the dark: COOL WORLD - It features animated and live action characters interacting together and at the end, an army of little dark ooze critters invades the real world.
I must admit, I'm surprise. I thought no one would get this, but you people impress me. Derf, you are correct! I just just check this out and it is the movie! Also funny that someone was also looking for this movie as well. Talk about a cosmic concidence.
To Jordan, you have somehow also solved another mystery of find without any knowledge and to my great surprise. The film you mention as one that I also vaguely remembered from the past as well. I wasn't even going to ask help on that one since I always remember two scenes from it and nothing else. Jordan, thank you for somehow solving a mystery of mine without even trying.
Anyways, the mystery has been solved! Thanks!