Man those places always screw up my order, but they usually give me something I don't want.
I ordered a bacon egg and cheese bagel and they gave me a steak and onion bagel.
Really? You serve that? Also, for breakfast? Hope your relatives enjoy stankbreath on top of morning breath.
Anyway, I think you're fine ethically. I always run into that problem. Here's another fine example:
I ordered food from Chili's as takeout. I come in and they haven't made my order, in spite of the fact they said it'd be done 10 minutes before. So, I sit down patiently and chat up the random hostess standing at the back. She says they've had a hectic night, and I say I understand, no big deal, things are fine. So then, a lady runs out of the back, calls my name, and hands me my order. I've already paid for it at this point, and she hands me two strawberry lemonades I did not order. I've had places do this a lot if you have to wait for a long time for your food. So, I thought to check my bag, and sure enough there was my order on top, the big mouth bites (basically sliders, or mini-burgers). My wife ordered something that was in a big container, so I didn't even check, I just saw it was in the big container, so I figured I was good.
I get home, and it's completely wrong. I check the ticket, and some other guy's name is on there. I sigh, and head back to the place. On the way I get a call, the manager apologizes, asks if there's anything they can do to make it right. I say it's no big deal, it's like a mile from the house, I'm okay, just let me have my food. They've already remade the other guy's order, so I get to keep the extra food. I'm thinkin' this is not a bad day.
Then I arrive, and the recriminations abound. The guy is furious I walked out with his order. The waitress is implying I am an idiot for not checking the ticket when she handed it to me, and walking out the door with two drinks I didn't order. The hostess I was chatting up is giving me a sidelong glance like I'm a complete moron. Just then, the manager walks up and is horrified that I'm going to sue because of the crowd of people who have suddenly turned on me. I just smile and say I was wrong... to trust the waitress when she called my name and handed me my order. She gets flustered and runs to the kitchen, the old guy and his wife calm down when they realize I just drove all the way home and back (again, only a mile, but in rush hour traffic off the highway), and that they were being senselessly aggro.
Then I get home and the wife starts making fun of me for getting the wrong order. "How did you not know?"
Can't win.
Moral of the story: people screw up. Most of the time you just keep moving. Anyone who judges you for it is a dick. Including your wife.