At the moment, all I can recall is what I believe is the ending scene from an animated movie from possibly the 1980s (maybe 70s): these characters are on a drawbridge and a young boy begins singing as everyone walks into the castle.

The singing is horrible and basically feels like a punishment for another character having to put up with it. I believe this is a running gag through the film, of these characters singing and listening (might be his older brother). The young kid might have a guitar.

I believe this takes place in medieval times, with castles, though not sure of the plot beyond that. It almost feels like it might have the Smurfs involved, though I may be completely wrong, and when I’ve researched actual Smurf movies, none seem to be right, at least plot-wise. Language is English in the film, though it’s possible a country outside the US made it.

This feels like a total shot in the dark, so thank you for any help!