Plot hole: Al comes home from work. He purposely doesn't look in the kitchen, so he can act like he's surprised it isn't Peg that brings him a beer. Steve talks and Al acts surprised that he's there. When you walk in the front door you automatically see the kitchen.
Suggested correction: It's quite possible to do this. My house has a similar layout: front door opens into the living room, and the kitchen is at the back of the living room. I can come inside and walk to the couch without paying attention to the kitchen. Plus, Al is cranky after work - he says "Ah, what a day" - and he is focused on getting to the couch and relaxing.
This is the only episode where Al does this... Just because he knows it's Steve and not Peg. Pretty obvious.
Just because something is only shown in one episode, that doesn't mean it has never happened before. And because he said "What a day", it seems that his work day was especially frustrating, busy, etc. It's reasonable that he could focus on getting to the couch, not bothering to look at the kitchen.
Continuity mistake: Marcy tells Peg that Steve has been gone for 5 days. Yet when he gets home, he has grown a full beard. It would take longer than 5 days to grow a full beard like that.
