Revealing mistake: In reality Deborah Messing is pregnant but her character is definitely not, so Grace has been filmed lately hiding behind big purses, pillows, counter tops, coats, etc. For some reason in this episode there was some rather sloppy shooting where Grace's waistline is concerned: When she and Karen are first entering the cabin, right after Grace says the line '...driving past 20 churches...' she turns sideways and for a few seconds there is a clear shot of her advanced pregnancy. Additionally, when Grace and Karen go to bed (also in the cabin) they have Grace lying on her back so the pregnancy is quite obvious in that scene, too.
Revealing mistake: At the end of the court session when Karen pulls the whoopee cushion gag, you see Will's chair right before he sits down and there's no whoopee cushion.