Audio out of sync after exporting from iMovie
I think I have a solution to your problem. I too was seeing this in iMovie and it turns out that if your audio track was sampled at 44.1 KHz, the export will likely mess up the audio sync. Fixing is quick and easy. Just take your audio track and resample it at 48 KHz. You can do this in a free tool like VLC. Then, bring in the new audio file, export your iMovie and it will work correctly.