Thanks to everyone who voted in the poll. It was kind of a trick question. :) No lie...
slaymesoftly and I thought we were going crazy. She was sure the door was wood, which it certainly looks like in these screencaps:
But I remembered the outside view from "Dead Things," in which Spike's door looks (to me) like weathered stone, though it could also be metal:
Also note the door has windows, with what looks like opaque glass and metal lattice.
On the inside, it's pretty dark, so it's hard to tell what the door looks like, but there's definitely no window:
Once Spike goes outside, the window is back, plus a cute little door handle that is distinctly different from the handle in OMWF (see above):
Patti and I were ready to call it sloppy set design and assume that no attempt had been made to match the doors on the exterior crypt set and the interior crypt set. Until we saw this:
Two doors!! An outer one (which I'm still not sure what it's made of) with the lattice windows and a cute little doorknob, and an inner one, which is solid and looks to be wooden. How is it that no one's noticed this before? And what kind of crack was the person who built this crypt smoking? Unless Spike installed the second door himself, why on earth would a crypt need a double door?
But I think the most significant thing about this discovery is that it puts the "Dead Things" door scene in a whole new perspective. Y'all thought they had some kind of connection, didn't ya? Well, turns out they were making love to different doors! lol
I wonder if that's supposed to be a metaphor for their relationship or something...
Oh, and one more for the conspiracy theorists - in "As You Were," Spike's crypt door definitely opens backwards. What do you suppose that means? ;)
Now, if you'll excuse me, I have to go rewrite all my scenes in Spike's crypt to account for his double doors...