In the 1970s there was a fair number of times when Marvel had to print a reprint instead of the intended story, but it was too late to replace the cover. Conan the Barbarian #22 is an example. The cover was supposed to go with the story in #23, and the issue carried a reprint of Conan the Barbarian #1 instead:
There are cases of mismatch from other periods as well. Detective Comics #40's cover was supposed to go with the second Joker story, but that story appeared in Batman #1 instead. So this cover was the Joker's first cover appearance, although he didn't appear inside:
This cover from Baffling Mysteries #8 belongs with a story that appeared in The Beyond #2 and was reprinted in Web of Mystery #27:
I thought it might be interesting to put together a collection of as many cases like these as possible. Please chime in with any you know.
This post displaced the thread 'Magic Order,' news from the homepage.
The cover of The Hooded Horseman #25 featured "Cowboy Sahib". This was a series about a Wyoming cowboy who becomes the ruler of a small state in the Himalayas.
The feature didn't debut until the next issue. The cover only says it's "coming soon", but it's possible the feature was supposed to debut in #25 and wasn't ready. #26's cover was based on a scene from the story, but it has a scene where the hero rides a tiger too.
The covers of #25-#27 were drawn by Leonard Starr, the feature's original artist. After #27 the title went on hiatus. When it resumed it continued a different title's numbering.
After Action Comics #1 the next Superman covers appeared on #7 and #10. The cover of #7 is a variation on a panel from Action Comics #1, from the sequence where Superman abducts Alex Greer. Superman's victim isn't drawn just like Greer, though. He had a moustache, and was dressed in a bow-tie and a plain, brown suit.