Beside the clothes, I will also talk about some curiosities of the movie! This bar really exists, its name is Redwood Bar & Grill! Is all decorated with naval theme, with many ropes, anchors, barrels and pictures of ships.
In the karaoke scene, there is a huge picture on the back of stage. Its a mermaid playing harp. and a ship in the background. The name of the picture is "Ship of death" from the artist Louie Metz.
I think the fact of Summer sing with mermaid picture in the background is related to the enchantment of the "siren song"?. By the way, did you know that it was Zooey herself who choose the song Sugar Town, Nancy Sinatra.
In the scene where they are at the table talking also has another mermaid frame made by the same artist.