Franchise Killer: This movie brought down both the original Tales from the Crypt television series (which had just been Uncancelled) and the film series as well after its poor reviews and box office. As a result, an eventual third installment (Ritual) went straight-to-DVD and initially had its ties to the franchise edited out. Another film (Fat Tuesday) had a completed script, but was canceled in pre-production (Word of God, though, insists that was due to other factors).
Though according to some rumors, Tuesday was finished...but was left unreleased.
Hostility on the Set: Reports say that Dennis Miller did not get along with anyone on set, even as far as being accused of stealing a set van to leave. Apparently heat between him and Corey Feldman got so bad that the producers had to force a distance between the two on set in between takes.
However, they do mention in Demon Knight that there was more than one key (in fact, SEVEN of them), and it's possible all keys look like that.
Also the end of the world was only if the demons got all the keys. Maybe this means we're permanently saved!
It is meant to be one of the keys, one was supposed to appear in each Crypt movie, but it didn't appear in the third film. The destruction of this key would also explain the Cryptkeeper's assertion in Demon Knight that Jeryline lives happily ever after.