My Brother, My Father - S3-E17
Other mistake: It's raining outside. Dorothy comes in the house and says "it's really coming down", then shakes her coat off although it's not wet. Then Stan shows up with an umbrella that's not wet. Then Sophia's brother Angelo shows up and isn't wet either. (03:20:50 - 03:22:45)
Answer: Ice makers were a new invention, advertisement purposes.