Dehydration Gun

The inverse of a Chekhov's Gun.

A literary device that would be perceived as vital to the plot of a story, only to hold little to no actual significance later.

Not to be confused with a Red Herring, which are used intentionally to mislead or distract the reader. A Dehydration Gun would commonly result from poor writing decisions, or plot holes.

The term derives from an item of the same name, in the movie 'Megamind vs. The Doom Syndicate', where it would have been a valid solution to many of the obstacles the movie provides, but is not used.

"Wait... Couldn't they have just used that thing from the beginning of the story?"

"I know, right? But no, it just turned out to be a Dehydration Gun."