No, the answer is obvious. Falco is just a that's forced into a costume to make .

No wonder he's a clone.

When you grab , he will have seperate eyes rather than the one eye, two pupils thing that he has going on. (Seriously, how does that work?) Plz help I think he becomes Sanic when you grab him.

Marth's upsmash has some stray pixels in the circled area.

There is some clipping in the right ledge of Lake of Rage.

The front face of the platform looks...odd, only while its moving tho.

Finally got courage to post it.
Sheik's walk has a lot of stray pixels in a lot of frames.

^

This one to be precise.

When Kirby has Luffy's ability the hat is normal colored until he uses the Neutral-B which then changes the hat color depending on the costume

Most of them make sense, like blue costume turns it blue and white costume turns it white.
But for some reason the orange costume turns it green.

This is actually side effect of the hat being part of kirby's sprites instead of the hat simply attached on kirby's sprites.
Few other copy abilites are like this too.

Not necessarily a graphical error, but it's still aesthetic so I put it here.
The heavy woosh sound from Tails' up-smash is still there, even though he's not using the mech for it anymore.

The end of 's spot dodge animation have those stray smokes.

Sometimes, after using a metal box, the character's palette changes.

This I actually think I have an explanation to
When the Metal Box is obtained, all the character's Color Adjustments (Hue, Saturation, Brightness/Contrast, Offsets, all that) are changed/reset to whatever the Metal Box wants it to be
And when they turn back, it seems the Metal Box forgets to adjust something back to it's original state (My best guess is Contrast) and so the costumes look different.
And here's a pretty fun part; This effect is actually semi-permanent, only going back to normal if you close/re-open SSF2. And it's completely online-friendly, they'll just see you as the character's normal color! So if you happen to fancy the new version of the costume over the normal, you can be absolutely free to have it your way.

Hyper saturated palettes are eye-stabbing. The one is especially nauseating.