The fact that Hap Shaughnessy's answering machine has a broken "rewind" button is a derisive-of-the-character joke all in itself --- the sarcastic implication is that the inflated-ego-steeped Hap was so fond of hearing his own voice imitating Gwyneth Paltrow that he'd actually worn out the machine's "rewind" function from backing up the tape so many times to re-listen to the recording. :P