When Violet goes out to try and get someone to listen to her tapes the second time, she is wearing a skirt and jean jacket. She then goes and signs up to play at a bar, and she is wearing the same outfit. But when she gets on stage, she is wearing jeans and a shirt. Then, later, she is wearing the skirt and jean jacket again.
There was a slip-up in the movie, but you also made one yourself. True, Violet goes out trying to get her tape listened to in a skirt and a jean jacket, but she is wearing a white button up shirt. When she goes to the open mic night, yes, she is wearing the jean jacket, but she is wearing jeans and a light purple shirt, which, could have been a different night, so she could have changed. When she was on stage, she was still wearing the jeans and the purple shirt, she just had taken off her jacket, as most people would. When she did go home though from the open mic night to find that her apartment had been broken into, she was wearing the skirt, white button up shirt, and the jean jacket. There was the slip-up.