Other mistake: During the closing theme (early seasons), when Fred walks by to close the birdcage, Wilma is shown in the background sleeping and her entire mouth is missing.
Continuity mistake: Throughout the first season, Fred and Barney's boss' name changes from George Slate to George Granite and back.
Continuity mistake: When Fred and Barney arrive at the Rockland Club, they park their car right in front of the front door. When Betty and Wilma arrive, they park their car in front of the door and Fred and Barney's car has disappeared.
Continuity mistake: When Fred and Barney are fighting over the television there are three knobs on the TV set, but when Wilma starts talking to Fred they have vanished, then they reappear.
Continuity mistake: When Fred and Barney arrive at the bowling alley, they are seen standing in the doorway, but the very next shot shows Fred inside the bowling alley and Barney is nowhere in sight.
Audio problem: At the bowling alley, there is a red haired man who is initially voiced by Alan Reed, but when he says "Hey guys! Did you get that?", he is voiced by Mel Blanc.
The Monster from the Tar Pits - S1-E7
Continuity mistake: When Fred comes in wearing the monster costume, there's a handle on the interior side of the door, but it vanishes when Fred hides to scare Barney.
Continuity mistake: Wilma opens the bedroom door to find Fred covered in flour, but in the next shot the bedroom door has vanished while Fred stands in the doorway.
Continuity mistake: At the 18th hole, Fred's opponent Ben Boulder hits his tee shot on the fairway. But we see Boulder doing his second shot, he doesn't hit the ball from the fairway; he hits the ball from the same tee box on which he did his first shot.
Continuity mistake: While sitting down at the celebration dinner, Wilma has a blue dress and Betty has a white dress. When they get up and walk away from the table, they've swapped colours.
Continuity mistake: The cake in this episode is first called "Upside Down Flint Rubble Bubble Cake." Later in the episode, it's suddenly called "Upside Down Flint Rubble DOUBLE Bubble Cake."
Audio problem: When the boys leave, Wilma says "Drop in some time to say hello" in Betty's voice.
Continuity mistake: When Wilma is serving the two steaks for Fred at the dinner table, you can see there is steam coming out of the steaks, but when she places them in front of Fred the steam has disappeared.
Other mistake: At the start of the episode we're shown a preview of the episode's plot: while Fred stretches his leg on the ballet bar his leg gets stuck and when the ballet teacher pushes his leg down, the part of the ballet bar which Fred is leaning on is gone. What's odd is that during this scene within the episode the ballet bar is perfectly intact. (00:00:25 - 00:14:40)
Continuity mistake: When Fred has a nightmare he drops his pillow on the floor, and just as Wilma gets out of bed to pick it up, Wilma's pillow simply vanishes into thin air mid-shot. (00:13:50)
Continuity mistake: During the circus performance, Rodney the knife thrower is wearing a one-shoulder outfit, which repeatedly switches from his left, to his right shoulder, and back again. (00:17:30)
Continuity mistake: When Fred introduces Wilma's book to Barney, the book is red, but when Wilma is reading the book in bed later, the colour is now green.
Continuity mistake: When Fred is reading his letter about his position being accepted at the Stone Valley Inn, you can see Wilma is sitting in the chair next to him, but in the next shot the chair is empty and Wilma is nowhere to be seen, then she reappears in the chair.
Continuity mistake: When Fred hands Barney the job advert he saw in the newspaper, Barney takes it with his right hand but a close-up of the advert shows him holding it with his left hand.
Revealing mistake: While Grandma Dynamite is on the roof sending smoke signals, Sonny is standing in the tree. When Sonny starts laughing we can see the bottom of his jagged clothing is now a mere straight line and his legs have vanished. (00:16:45)
Answer: The name of the pet is "Baby Puss." He has appeared in episodes, but only a very few. The first episode was probably "The X-Ray Story" from season 2.
Bishop73