In the original SNES game, one of the "junk" items that Rush can dig up with Rush Search is a Game Boy. This is removed from later versions in multi-game compilations, as many of those compilations were also released on non-Nintendo systems.
The version re-released in 2004 as part of Mega Man Anniversary Collection replaced the word "damn" with "darn." It's possible they wanted to avoid a "mild language" qualifier on their "E" rating. This was also present during the later Mega Man compilation game Mega Man Legacy Collection 2 (2017) (VG).