When Ralph is stopping the crooks' AMC Matador, in the closeup shot of his feet he is stopping a Ford Van.
It makes no sense for the aliens commandeer Pam's car as shown. In fact, there was no reason for her to go out to the desert in the first place since Bill was already with Ralph. Then later on, it makes no further sense for Pam to leave her car there and ride back in the weinermobile with Ralph and Bill.
When the Nazis are experimenting on the suit, they try burning it and shooting it, to no effect. This either means that the suit only works when it's worn by Ralph or nobody - or that it would be bulletproof and fireproof for anyone who had the suit on.