Snoops (Joe Flynn) passed away in 1974
So I think that's were the confusion comes in on when the film was made as they must have did most of the work in 1974 and then released it in 1977...
shareApparently so... It often does take a few years for an animated film to be in its stages of production, and since voice acting is one of the earliest steps (before the animation begins, usually), this does make some sense.
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