The real Samuel Clemens (a.k.a. Mark Twain) appeared in TNG: “Time’s Arrow”.

I’m pretty sure an actor appeared in Time’s Arrow

Well I’ll be damned, the first part is real, at least: https://memory-alpha.fandom.com/wiki/Headgear

It probably boils down to Boimler being a sad sack who still isn’t confident enough to stand up for himself.

Scary Door

In B4 Piped Bot: https://piped.video/watch?v=bH10TsgozG8?si=9i_hCycJwVzm9qVb&t=132

Hmmm, I wasn’t quite sure about the Futurama reference at first because Bone Vampires/Moopsies aren’t exactly unique types of legendary creatures, but then Ransom said “Turns out humans are the most dangerous” which is a straight up lift from the Scary Door.