Apple - How to fix iTunes wrong song time?

The incorrect time is most likely due to an error introduced by the encoding software. You can repair the problem by using the Convert to AAC feature in iTunes.

In iTunes 11 this feature can be found under the Create New Version → option of the File menu.

How can I fix incorrect mp3 duration @ askubuntu had a couple of command line solutions.

For me, the ffmepg solution worked (ffmepg can be installed to OS X with Homebrew, for example):

ffmpeg -i file_orig.mp3 -acodec copy file_fixed.mp3