http://www.memorylossonline.com/spring2002/memlossatmovies.htm
In important ways, Memento depicts amnesia more accurately than any major film release to date. But it also contains a few notable errors, offering an opportunity to set the record straight on a much-misunderstood memory impairment.
plot point in Memento that doesn't quite ring true is his vivid memory of the physical attack in which he was injured. People with anterograde amnesia often cannot remember the trauma that caused their memory loss as well as some memories of events just before the trauma.
