John Cena admits that he has a fear of heights. One of the scenes revolved around him rappelling down the side of a building and then dangling from a rope in mid-air. On a DVD extra, Cena said shooting this scene made him so uneasy that he almost quit the film.
Taking from something from Cena's wrestling career, anytime a cast member messed up they had to do push-ups for whichever person they wronged, and say "I am '(name of the person wronged)''s bitch!" after each one.
The scenes where Danny is driving the fire truck were done with John Cena in the cab, but a second steering wheel was hidden in the cab where a stunt driver concealed off camera controlled the vehicle.
John Cena is the third WWE Superstar to receive a role in a WWE Films (Studios) production. Dwayne The Rock Johnson was the first with Walking Tall and Stone Cold Steve Austin was the second with The Condemned.
John Cena explained in a interview plus on the commentary track on the DVD that he was looking to do another film after finishing The Marine (2006). This film was pitched to him by producer Josh McLaughlin and John became very interested. He continued that this movie was better than The Marine despite he enjoyed working that film and likes the movie. The main reason this movie because, according to Cena, was that it tells more of a emotional story and the audience would have a strong connection to the characters. At the same time, the producers also wanted a non-stop PG-13 action film like The Marine.
Originally the dog owned by Molly Porter (Ashely Scott) and Danny Fisher (John Cena) named Shorty was going to be a bulldog. The producers changed the dog to a pug when the filming was done as pugs can be mistaken for bulldogs.
According to Renny Harlin on the DVD commentary that all the producers were against having a pug in the movie until Renny pitched it to John Cena who thought it was a great idea. Daniel Kunka explains on his own DVD commentary that when Renny pitched the pug, he was against it so much that he decided that it would be a Bulldog and kept that in the script until Renny changed it to the pug.
Renny Harlin: [Finland] Numerous reference to Renny Harlin's native Finland, such as the mentioning of Helsinki in dialog, a Finnish flag on the side of a motor home at the location of a car crashing into a boat, etc etc.