When the police arrive at Joe's, the policeman wearing the sunglasses is wearing a police hat when he is outside the door. Going through the door, he no longer has a hat.
Even though the characters are shooting you heroin, none of them appear to be high.
When June and Wanda first pull into the gas station and the attendant speaks to them through the passenger side window, his dialogue is obviously looped as the words don't quite match his mouth movements.