There are several possibilities:
1. You might be thinking of a different film with a similar title. Perhaps it was released in a different year, or had a slightly different title. Could you provide any more details, like the director, genre, or a brief plot summary?
2. "Circus" is a very common title. There might be several films with this name. It would be helpful if you could specify which "Circus" you're interested in.
Once I have more information, I can help you find the cast list.