What did Rashad originally think the officer in the store was yelling about? When did he finally realize the real reason?

At first, Rashad thought the officer was yelling at the woman because her bottle broke in the fall. When he saw the man was looking at the bag of chips and the open duffel bag, however, he realized the yelling was directed at him... the the officer was accusing him of tripping the woman on purpose, and that he was stealing.