Anime Superhero Forum

Of course. Since Mickey Mouse Works (from where most of the shorts played as part of House of Mouse were sourced from) was originally produced in 4:3 format, they cropped those to widescreen when the HoM episodes were originally produced.

The 16:9 croppings were then cropped to 4:3 when the show aired in fullscreen format.

I am shocked that the Mouse Works shorts were able to sustain themselves being cropped twice. I myself was shocked finding out most of the Mouse Work shorts (besides a few) were actually made in fullscreen.

and it took me some time to find out those cartoons shown in the House of Mouse were originally from another show and I was a bit shocked as well

Some shorts (Mickey’s Big Break being one of them) actually had some shots in 16:9 and some shots in 4:3 in the same cartoon!

well, there were actually some shorts that were produced directly and aired as part of House of Mouse. Like "Lil' Bear", "Hot Tub Humphrey" and "Mickey's April Fools". The one you mentioned ("Mickey's Big Break") was aired on Mouse Works before, so Idk how it has shots in both formats.

A short that was actually made in widescreen was Roller Coaster Painters

It may be because it was released theatrically (like some other of these Mouse Works shorts actually were)

Roller Coaster Painters was released theatrically? Source?