Actress Joanna Lee (Tanna) is seen cracking up in the background when Eros exclaims "You're styupid minds! Styupid! STYUPID!" Joanna Lee's main career was writing for children's cartoons, and she created the character the Great Gazoo. It's probably no coincidence that she was the one to lose it during that scene, since she must have had a big appreciation for campy humor.
Ignoring the numerous physics goofs in the movie, if the sunlight-exploding device is so easy for any old primitive species to create and is an unstoppable weapon, why hasn't another alien race in the universe built one and turned it on? How do they even know such a device would work without evidence?
Presumably, previous discoveries of the solaranite effect were made in enclosed areas with only artificial light to detonate.
Why does the old man wear a Dracula cape? Why doesn't the airplane's cockpit have control wheels? Why does it switch back and forth from day to night within seconds? If we tried naming all of the examples of Fridge Logic from this movie we will be here all day and night.
With the aliens defeated, nothing is to stop the humans from inventing the solaranite and wiping out the entire universe. Since this is the Ed Wood universe we are talking about, the Fridge Horror comes from the fact that the aliens almost succeeded in stopping them.