@sawibis659: I looked it up in SMILE and there indeed is no such purple colour in the game at least one which matches with the doors (there are some close colours but they're either dark purple or slightly more reddish than the missile door). In reality, the colours are taken from the purple item drop which is particularly true when you consider that these doors' colours are multiples of 8 (implying to be edited with YY-CHR or something) while the others aren't (implying they're taken with a colour corrected emulator like BSNES unlike ZSNES).

You're also right that the Gravity Suit is missing (and let's be honest, the whole section is a mess).

Is it just me, or is this missing the gravity suit?

(@MarioFanGamer Are you sure the purple doors are not just an unused palette?)

It certainly is a custom one, likely inspired by Super Metroid Redesign which does have purple doors.

I'm curious as to where there's a purple door on Zebes. I have no recollection of one.