Spaced Invaders isn't really a parody. It's more an outright comedy about some idiot aliens who come to earth and hear a re-broadcast of "War Of The Worlds" and think they are hearing about their own invasion so they try to takeover this small town. This happens on Halloween so the townsfolk just think they are kids in costumes
The only alien who has a clue has a funny take-off Jack Nicholson voice and the best dead-pan lines. Him and the kid in the duck suit are the best parts.