In the last 5 minutes of trading GOOG seemed to take a nosedive from 400 to 250. Luckily NASDAQ came to it's senses shortly and flagged this as an "possibly erroneous trade", but with this market I'm sure I wasn't the only one thinking ohh crap..
The NASDAQ Official Closing Price in GOOG will be adjusted to $400.52. This will be reflected on the tape shortly. Clients who had executions in today’s closing cross in GOOG will get the shares at the adjusted price ($400.52) in clearing tomorrow, and will receive an electronic break today. Any questions please call Market Operations at 212-231-5100.
The best part of this whole thing (thanks to RainbowShrimp for the tip) was this post on Google Forums: