Plot hole: The FBI in the movie has the ability to "blackhole" an IP address, which makes that computer unavailable to the internet. If they can blackhole the computer acting as the web server, they could also blackhole the computer acting as the name server (DNS), thereby taking down the web site and preventing additional users from connecting.
Great sites
Mistakes
In the beginning the detective is a detective but during the exciting hunt for the killer (when Diane Lane's character is abducted), the detective is referred to as a Lieutenant by his people over the radio. See more...
Untraceable mistakes
Plot hole: The female FBI agent runs to get someone who understands Morse code to work out what the one person is saying. Surely the FBI would be recording the video, so why panic?
Other: After Marsh wakes up and she turns on her notebook to search for movies related to "OUR SUICIDE" note, she plays one, and on WMP the "play" button should switch to the "pause," which normally occurs when playing a video using Windows Media Player.