Most of the bad movie laughs in this film are a result of either its attempts to be cute and endearing, or of the most shameless marketing I have ever seen. One of the aliens gets splattered across a chain link fence in one of the movie's more ludicrous scenes. There the movie begins in earnest the film's attempt to be cute and endearing. Perhaps the filmmakers were trying to break from this cliche, or maybe they needed to make the kid more sympathetic, but, whatever the reason, they make a big deal about his being in a wheelchair, even though this fact doesn't advance the plot or make the character more likeable at all. In fact the only time it's important is when he rolls off a cliff in his wheelchair, and Mac saves him with his special alien powers.
Most movies have some sort of product placement.
This movie features the most overt example of this in film history. Coke just won't do for these aliens, who, while not speaking a word of English, are quite adamant as to what brand of soda they need to survive. Anyway, wheelchair kid gets shot and killed by the evil military guys. Then Mac brings him back to life, and the military guys just walk off.