A piano appears in the Flintstone's living room just in time for Wilbur to play it and in the next scene it disappears.
Fred leaves the house to go bowling with Barney but doesn't take his bowling ball.
In this story Fred and Wilma claim to have been married for nine and a half years, but in season one they celebrated their tenth anniversary and later in the run their fifteenth. They should be approaching their twentieth by now.