When they are reviewing the profiles one that comes up is Sean Furst, who is one of the movie's producers.
When Katherine is trying to crack the files about halfway through, she runs a hexdump and it lists out several dozen ASCII bytes separated by percent signs. This is easily decoded to say "Hello Richard, my name is Mark and I think that you are very fat indeed and sometimes you smell as well" two times (with no separator in between, so it says "wellHello" in the middle).
The film's opening prologue reads: "Since World War II, intelligence agencies have used secret stations to send encrypted assignments to agents in the field. Unlike digital and cellular communications, these shortwave broadcasts of encoded numbers are untraceable. Governments deny the use of such stations, but the numbers can still be heard today."
The film's closing credits declare that the picture was: "Filmed on location at Bentwaters Park, Suffolk and at the War Museum, Suffolk."