Finally took the time look at the issue with attached files to the new techdocs. Turns out it was really easy - unless you specify a file extension, the mirroring script used to generate our static mirrors gets confused. Only the instructions told the person adding the files not to use an extension when referencing them. Oops.
While at it I also fixed the problem that it didn't return 404 for missing attached files - instead it returned a proper HTML page that said the file didn't exist. Which was then dutifully mirrored by all the static mirrors. Oops again, but another very easy fix.
Sometimes it's just so easy to find the bugs your code. Sometimes I wish life was that easy to debug...