The most memorable scene, of course, being from the very beginning which sets off the entire chain of events.
Mom: Oh dear, I think I left the garbage out overnight.
(both run out to the curb)
Dad opens up the garbage can, only to find it empty.
Dad: Oh no. Someone's stolen our garbage again!
Another of my favorites is when they mistake the janitor at the planetarium, Lloyd, for God, and apologize for having pronounced it wrong all these years.
Oh Tom Arnold, you comedic genius you.