No, if you enter the MK sometime after 4 pm, you usually go thru a special turnstile, where they'll check your MVMCP ticket and put an armband on you. The armband will allow you to stay in the park after the park closes, usually in the Tomorrowland area. If you are already in the park and you have dinner reservations, they will check your ticket at dinner, and give you an armband. If it is before 7 pm when you finish dinner, they will ask you to go to Tomorrowland, or wherever they are 'herding' people!