Revealing mistake: In the dance off scene when Rose is doing cartwheels, you can see it's Betty White's stunt double.
Revealing mistake: When Dorothy and Blanche are in Rose's room, look at Baby. Its very obvious its just a stuffed toy pig. You can tell by the fluffy skin, the unnatural ear movement, and the covers would be moving up and down as its breathing. You can really tell its fake when Rose gets up off her bed. (01:08:45 - 01:10:25)
Revealing mistake: Dorothy is cooking on the grill in the backyard. Problem is the grill isn't really "cooking" the food. No smoke, no sizzling. And the food is hard like it's frozen solid.
Revealing mistake: Dorothy brings out a pot of coffee and pours it into cups. When her friend Barbara is leaving, Dorothy is holding on to the "hot" coffee pot like it's not even hot. (00:07:50)
Revealing mistake: In this episode Dorothy and Blanche are awakened by a stench coming from the kitchen. After they go to inspect, we see that Rose is making some sort of Krispies treat. As you see her carry the plate to offer Dorothy and Blanch one, you can see that the plate is empty. And once they all start to eat them you can easily see that none of them are actually picking anything up and putting in their mouths.
Answer: Ice makers were a new invention, advertisement purposes.