I believe this mistake occurs during a conversation between Cleopatra and Antony. The two are talking in an outside setting, and the next scene has them in Cleopatra's palace-with the queen in a new outfit! In the very next scene, Cleopatra has switched outfits yet again!
If you're talking about what I think you are talking about, this was most definitely not a blooper. It was showing how angry Cleopatera was at Antony and one could see that they were arguing for several days.