The inverse of Chekhov's Gun. An item seems like it has meaning, but in the end, it turns out it doesn't.
A Chekhov's Gun is an item or concept which seems inconspicuous at first, but eventually is revealed to have great importance. The Chekhov's Squirt Gun is the direct opposite. A Chekhov's Squirt Gun may seem to hold the key to a secret or possess great power, but in the end, is revealed to be yet another worthless red herring.