A couple of thoughts:
1. So these guys totally traded places and filled in for each other at home. What if Joan Allen was like, "Honey, can you go to the store and get me my favorite chewable anti-gas tablets?" and then Cage as Travolta was STUMPED. Like, dude, you've been outed, you've been found out, you're fucked.
and 2. I'm wondering if perhaps the hit TV show Wife Swap took any inspiration from this film.