what to do if you hit "play" before rental movie has fully downloaded?

last night i hit "buy" on the itunes store for a HD movie. this morning i checked my rental tab and it showed the movie thumbnail and synopsis. i boarded my plane and eagerly hit "play". the 24 hour warning dialog box came on, i checked it and waited. i get a message the the movie is now downloading and it will take 86 hours. but i have only 24 hours to watch my movie. i wrote to apple support. but has anybody ever encountered this before?