I just finished God of War, and noted that the game is rated M for, among other things, "strong language." While the game certainly earns the M rating, the only "strong language" I noted was one usage of the word "pissed" in some of the bonus features.
Meanwhile, Resident Evil 4 does not have a "strong language" notation, and it contains a dozen or more uses of stronger profanity.
In addition, DDR Extreme is rated E for "mild lyrics," despite the very obvious use of the F-word in one song.
Can you think of any other games with problematic ratings?