 CONT: Throughout the movie, Mark and Rogers answering machines  repeatedly switches between answering after one ring and answering  after two rings. A person could argue that the number of rings was  changed by either Mark or Roger, but at the beginning of the movie,  on Christmas day, it rings a different number of times for Maureens  call than it does for the call from Marks parents, and no one has  made any changes to the machine.