Learn English – What does it mean when someone says “your brain must be full”

Sometimes people set a trap in order to force others to make a mistake or own up to the truth. An English idiomatic phrase that fits this type of situation is to trip someone up; if the victim falls (unwittingly) into the trap, then you have successfully caught him/her out.

set a trap (for somebody)
a clever trick that is used to catch someone or to make them do or say something that they did not intend to

catch out
to show that someone has made a mistake or is not telling the truth, especially by asking them questions He asked her casual questions to see if he could catch her out.

_{Sources: Longman Dict. of Contemporary English, Macmillan Dictionary}

It isn't a common idiom, and I haven't seen the film, but from the tiny bit of context you've provided I'm guessing that the intended meaning of "to circle" here was "to move in circles around", and that the whole statement was saying, by analogy, that there is a limit to how long one can avoid dealing with an issue.