Why did he drive?
I get why Mitch drove his car back home, that was a plausible reason (dumb move but plausible). What I don't get is why he drove there in the first place? His wife says to him "you promised to take a cab" so that suggests he knew he was going to get drunk and not be able to drive home. So why did he drive there in the first place? Wouldn't the smarter option have been to get a cab there? Or get the guys he was going out drinking with to pick him up? Or even have his wife drive him there drop him off and then drive home.
It just seems silly to me that, they would set up a plausible reason why he would drive home drunk, but have no plausible reason for him needing to drive there in the first place.