Google the name "Yuval Aviv" There's a lot of stuff out that he's the "mossad agent" the movie is based on, and that he's a fraud.
Anything where the film makers defends the use of this material?
Interesting stuff on this Yuval Aviv
http://64.233.179.104/search?q=cache:svtHmzPCIRsJ:www.haaretz.com/hasen/spages/596350.html+%22Yuval+Aviv%22&hl=en