Continuity mistake: When Ernie is putting in the heat lamp, there is one part when he is holding a piece to it, and reaches up to put it in. In the next shot or two, he has it and puts it in again.
Girl Fight - S2-E15
Continuity mistake: When George goes to meet the counselor, the counselor asks George if he wants a piece of pizza. The piece of pizza the counselor is holding changes after 2 shots. The first two shots show him holding a full piece of pizza with no fold in it. The last shot shows him holding a piece of pizza with a bite in it and it is folded.
Continuity mistake: At Thirsty's, George's brother is drinking a beer with a dark-coloured bottle and red label. It frequently switches from a red label to a green bottle with a yellow label and then back.
Answer: His last appearance was in the episode "God Needles George. He had a tumor in that episode, but in the end was better, and that was the last appearance of him on the show. He was occasionally mentioned afterward, so it is assumed that they still had the dog for the rest of the series.