Same explosion used twice
It's been nearly a decade since I saw this movie and laughed my ass off, so I going from memory.
There is an explosion inside the spaceship, I believe in the same scene that the guy gets his face flattened by a frying pan?
They use that exact same explosion at the end when the Leprechaun blows up in space. But it's so obvious because you can see the inside of a ship in the background.