All bar scenes across the entire film were shot in the same Taipei bar called Twins where local Taiwanese and ex-pats would actually patronize
Because of the typical small budgets for Taiwanese films, the director smartly reused all extras in multiple scenes within the same location, and further, in multiple positions within the same scenes, assuming the audience would not be paying enough attention to realize it. Extras would bring a change of clothes to the set. In some cases, the same extra could be seen on both sides of a conversation at the same bar: on either side of the main 2 actors, just in different shirts.