iMovie 3 for Mac OS X (Visual QuickStart Guide)

Unfortunately, iMovie 3's audio seems to experience the most or just most frustrating problems.

Video and Audio Out of Sync

If your audio and video are out of sync in a video clip, try extracting the clip's audio track, which locks the audio to the video (see Chapter 10).

Audio Problems When Exporting

Are audio fades not working after you export your movie? Or perhaps clips you had marked as silent are still playing after export? The fix seems to be to have one clip selected in the Timeline when you export your movie, believe it or not. Hopefully, this (and other bugs) will be fixed soon.