A pimp goes to hotel room #823. Exiting the elevator, he walks to the and opens the door to #823. The signs outside the elevator show rooms 816-830 being on the right, not the left.
Tyler has a "cross" tattoo behind his left ear; it's not visible when he follows the girl into her hotel room.
Denver International Airport did not have an on-site hotel at the time the film was made.
When Tyler hangs up the pay phone in the "Denver" airport, we see that he has been using a rotary pay phone.
(at around 27 mins) In Rachel's apartment, a black-shirted cameraman is visible in the closet mirror.