Continuity mistake: Nadine puts a plate on the table with an apple and a sandwich. The apple is on the right and sandwich is on the left. The next time we see the plate they have switched sides. Nadine then takes a bite out the apple and puts it on the table. The next time the apple is seen it has moved.
Grace and Rick and the Dance of Doom - S3-E3
Continuity mistake: The milk carton Quentin puts on the counter keeps changing position.
Continuity mistake: When Matthew's adoptive mother gets up to leave, her purse strap is on her shoulder. When she walks to the front door, turns to Grace and says "listen lady" she's not wearing the purse. When she turns to open the front door and walks out, she's wearing the purse again on her shoulder. (00:11:40)
Continuity mistake: Quentin comes into the basement, the door is open. The next time we see the door it is closed.