Bob's father's pendant fires the beam, then it appears that it was just Bob getting an Eleventh Hour Superpower in a Die or Fly moment. But the pendant was still important in that thinking of his father gave Bob the Heroic Resolve to manifest the power.
There is a gun on the wall and it's shot thirteen minutes into the episode, but it misfires. The hero pulls a heretofore ignored knife from his ankle sheathe, but he is quickly disarmed. Seeing a lever on the floor that he previously tripped over, he pulls it, dropping the villain into a pit of acid.
All plot points are laid out in an obvious manner, and there are no plot twists.
There is a gun on the wall in the first chapter. It has no significance and is never mentioned again.
"We want to sell toys based on The Movie, so have one of (shows object) turn out to be important".
The gun from a previous episode becomes important later because the producer noticed a pronounced fan response to the gun.
The hero, a Chekhov fan, picks up an old, useless-looking gun he sees, hoping it will come in handy later.
Defied: The hero sees the gun in the middle of the climatic fight scene thirteen minutes into the episode, but ignores it because he thinks Chekhov's Gun is trite.
Discussed: The hero notes out loud that the gun on the wall ought not go unnoticed.
Conversed: Characters in a room with no hidden significance are waiting for their tea. They talk about the use of Chekhov's Gun in a play they saw.
The gun doesn't quite cover all of the heroes' needs when it's used.
Bob figures out the medallion he bought at the beginning of the episode is the key to victory...pity it seemed so insignificant he left it in its glass case before heading out to face the Big Bad.
The gun is an ornament, when it is grabbed ten minutes into the episode by the hero, who is shocked to find it doesn't fire. He uses the replica as a club to kill the villain, then bar the door as he escapes through the back.