Brennan On The Plane?

I haven't seen this mentioned anywhere else, but it was (potentially) such a huge plot hole I thought I'd bring it up.

When Brennan follows Reilly, Valentin and the other copy to Puerto Rico he is seen standing in line behind them to board the same plane they are. The next scene we see is the cops exiting the airport in Puerto Rico with Brennan close behind.

They don't actually show any footage of the plane ride, but ask yourself, how on earth does a guy as big as Brennan, known very well to all 3 officers, dressed in the same clothes as he always is, no hat/sunglasses/mask, manage to keep hidden during a, what, 3 hour plane ride?

If they boarded before him there's no plausible way at least one of them doesn't spot Brennan as he boards. If they board after Brennan, does he hide in the bathroom for the entire flight? Even if he does, how to explain that they don't spot him in the terminal after the landing?

I know this is a lot of text about a minor point, but sometimes I marvel at how directors will completely overlook the logical and just assume the audience will never notice.