Steve gives Al a fish for him and Marcy and say they barely eat red meat. In season 1, they said they were vegetarians.
When Al and Peggy are planning the cookout in the kitchen behind Al's left shoulder you can see the shadow on the wall of a dog tail up the stairs.
At the end when they are all eating the hamburgers, Al's burger is missing, it's just two buns together and he's acting like he is eating it as the bites are still the same on the bread.