Continuity mistake: When Barney is knocking on the door at Fred's house after seeing an advert in the newspaper, Fred says "I'll get it, Wilma!" and stops near the door. At this point, Fred is well away from the door, but in the next shot he is now standing near the corner of it.
Continuity mistake: When Wilma and Betty are looking at the jobs in the wanted ads, there is a purple cloth between the green and pink cloth on the washing line, but when the two are looking at Dino playing with Pebbles, the purple cloth has disappeared. There's also a basket by Wilma that moves to the end of the washing line.