I think the cartoon movies main character was a mouse, but I can't remember. I just remember one scene (I remember seeing this on HBO probably in the early 80s).

The scene was a couple characters looking at an old tin can with a label on it. The label had a picture of the tin can with the same label on it, and the characters made some philosophical comments about how the image was an image within an image on and on forever and ever to infinity or something.

Do you know what movie this is?

The Mouse and His Child (1977)