Hero - This character is a border patrol agent (protecting Earth from 'illegal' aliens, so to speak). He should have a voice of authority but also a whimsical tone when odd things happen to him. He doesn't speak a whole lot and what he does say will be general stuff that you'd expect a border patrol agent to say. Some sample dialog would be:
"Remain in your home Miss, I'll handle this."
"Terran Border Patrol ... land your vehicle and come out with your hands - er - appendages raised!"
"You're under arrest for attempted body snatching, cattle mutilation, destruction of agricultural products, assaulting an officer of the Terran Border Patrol Agen ... HEY!" (agent gets captured by grappling device on the spaceship and a small propulsion device stuck in his butt. After a brief flight through the air ending with a hard slam into a tree, head first, he continues his list of charges wearily) "... and anal probing."
Also need several versions of the agent gasping, grunting, screaming, and whatever else you can think he'd do while pursuing or being pursued by the aliens.
Aliens - Both of the aliens speak in a language that is not recognizable as any Terran language (you should have a lot of fun with this one making odd noises and sounds that define the characters language and audio cues to their emotions). The conversations should not be long and consist mostly of sounds that would accompany their body language. To get into the characters, remember that they are the equivelant of teenage hoodlums. They're here on Earth to cause havoc and do things that rebel teenagers would do if their parents left town for the weekend.
They'll laugh, be amused, perplexed, annoyed, interested, sick (physically ill) and congradulatory towards each others mischevious doings.
Mom - Mom is not intended to be a speaking role but if you feel the need to ad lib something appropriate go right ahead. Mom is basically the victim of an attempted body snatching (along with her baby and the entire trailor that they live in). She'll be settled down in her fold out bed getting ready for sleep (maybe reading a book or the National Inquirer). Remember the scene in Close Encounters where the light comes on over Richard Dryfus' truck and he's freaking out that maybe his truck will suddenly lift off the ground? That's about what we're going for here only she'll be a little more panicked because the event involves her child and entire home.
We'll also need a "ugh" or other suitable sound of relief after the agent disables the alien ship's tractor beam sending the trailor on a fast trip back to the ground. She'll exit the front door with the baby in hand to be intercepted by the agent (see "Remain in your home ..." above).
Baby - The baby is a baby. He's totally oblivious as to what is happening or old enough to percieve the event as a threat. He should laugh and giggle as a baby would if he suddenly found out he was capable of floating (which is what he'll do under the effects of the tractor beam).
animals - Cows moo, cat meows. Simple huh? OK ... just to be difficult. The cat also shrieks in terror. One of the cow undergoes a series of gene altering mutilations. It will "baaaa" like a sheep, "aih-aih-aih" like a dolphin and "meow" like a cat (but be confused at the results of each mutation).
possible addition of extra character - I'm also thinking of adding a quick scene in the trailor park that will involve a pair of kids and their parents. They will basically witness the agent being attacked from their bedroom window. At which point one of the kids will yell to their parents watching Jerry Springer (or other silly program) on TV, "Mom! Dad! Aliens are attacking the trailor park!"