These are the comics that were posted on xkcd where the release date is unknown.
- comic #36 was originally posted as a duplicate of comic 10: Pi Equals.
- This was corrected some time between April 22, 2006 and July 5, 2006 when the current version 36: Scientists showed up in the web archive (see the links). See also the trivia section for that comic.
- There has so far been no way to determine when Randall made the correction, and thus posted the comic.