...that "the head" means "the toilet" in American English :)

I'm UK English, and when I played this game as a kid I had NO IDEA what the heck the game wanted me to do... There I was, on a German U-Boat, and the game just kept saying "Go to the head"... Not helpful when you've no idea what that means.

I was convinced it meant: go to the BOW of the sub. The "head" of the sub = the front of the sub ... that's logical, right? But, no... And there was no internet to turn to for a "translation" back then, either :)

Honestly, that bit of unfamiliar American slang had me more confused than any of the actual puzzles! Good times.

Actually, it's a Navy expression.

You're absolutely right... The expression "the head" is also used by the Royal Navy, it seems - so, yes, it's navy slang, not American slang. Still livin', still learnin'! :)