Manholes can be found in Epic Mickey 2: The Power of Two and Epic Mickey: Path Painter as gameplay elements, and in Epic Mickey as part of the scenery in Mean Street.
There are manholes at the ends of some of the streets in Mean Street. Thinning the top of one of them reveals an E-ticket underneath.
Epic Mickey 2: The Power of Two
Manhole covers lead to the D.E.C.. They appear in a variety of places, mostly before the Projector Screens are repaired.
Epic Mickey: Path Painter
Manholes automatically respawn Spatters continuously. They can be thinned over to prevent anymore Spatters appearing.