Ghost Rider VS Lobo (Marvel VS DC) - S6-E10
Audio problem: When Ghost Rider drives up and points at Lobo, he starts speaking. His mouth is moving, but when it cuts to a different angle just before Lobo runs him over, his mouth is now not moving while he's still speaking.
Black Widow VS Widowmaker (Marvel VS Overwatch) - S6-E3
Factual error: When Black Widow and Widowmaker fire the sniper shot at each other, there is a close up of the bullets grazing each other in mid air. However in this shot the bullets are animated as having the casings still attached while flying through the air. (00:15:30)