In episodes 21 and 22 (at least towards the beginning of the latter episode) of the "second season", we see Kaiki in a number of shirts in the same scene in the Okinawan cafe.
He first appears in a pink shirt (which he wasn't initially wearing in the airplane):
Before changing to a blue shirt and a yellow shirt:
In the toilet, we see him in what appears to be a different pink Hawaiian shirt, and in the beginning of episode 22, we see him in an orange shirt:
The changes in shirt seem to coincide with "pauses" in the conversation - e.g. pauses indicated by the "black screen", or Kaiki's own thoughts (accompanied by images such as departing airplanes). But the conversation between Senjogahara and Kaiki probably takes place over a bit more than the course of one afternoon. If that's the case, should Kaiki's changes of shirt be taken as something stylistic without much meaning, or is there some significance to it?