This all occurred on original hardware, including an original Platoon cartridge in an original NES.

I inserted Platoon into my NES and turned on the power to see the glitched graphics that one can normally expect when the cartridge is significantly out of alignment, but I also noticed that the graphics didn't correspond to the title screen. It turns out that the game was starting at the victory sequence at the end of the game!

Dwedit did some analysis and came up with a plausible explanation very quickly (which I will paraphrase as it was spread out over several messages):

'The game runs the ending whenever it executes the beginning of bank 0. My guess is the prg "write" pin was disconnected, so none of the mapper writes (bankswitching, etc) were taking effect, so it was booting to the default program page, with the default graphics page, and the default mirroring state, and it ran the ending with the wrong graphics bank. Specifically, cartridge pin #14 was not connected properly (likely from dirt on the cartridge or in the system). I'm not sure if putting tape on that pin would reproduce it, all I know is that the mapper writes weren't taking effect, and that's my guess as to why.'

Major thanks to Dwedit for doing such swift research into this unexpected issue. Although I rarely ever run wrong warp categories, I felt it was the right thing to do to create this category so that people can find out about what is, to my knowledge, essentially the first 0-frame wrong wrap in an NES game. If anyone can use the above information to recreate this glitch, they are welcome to submit it here. (Enter the time as 0.001 seconds, as 0 seconds is not considered a 'valid time' by the site.)