of the Worlds in late 2004, Spielberg met with stunt coordinator Vic Armstrong, who doubled for Ford in the previous films, to discuss three action sequences he had envisioned. However, Armstrong was filming The Mummy: Tomb of the Dragon Emperor during shooting of Kingdom of the Crystal Skull, so Dan Bradley was hired instead. Bradley and Spielberg used previsualization for all the action scenes, except the motorcycle chase at Marshall College, because that idea was conceived after the animators had left. Bradley drew traditional storyboards instead, and was given free rein to create dramatic moments, just as Raiders of the Lost Ark second unit director Michael D. Moore did when filming the truck chase. Spielberg improvised on set, changing the location of Mutt and Spalko's duel from the ground to on top of vehicles. The Ark of the Covenant is seen in a broken crate during the Hangar 51 opening sequence. Lucasfilm used the same prop from Raiders of the Lost Ark. Guards were hired to protect the highly sought-after piece of film memorabilia during the day of its use. A replica of the staff carried by Charlton Heston in The Ten Commandments was also used to populate the set to illustrate the hangar's history. Effects Producer Frank Marshall stated in 2003 that the film would use traditional stunt work so as to be consistent with the previous films. CGI was used to remove the visible safety wires on the actors when they did their stunts, such as when Indy swings on a lamp with his whip. Timed explosives were used for a scene where Indiana drives a truck through crates. During the take, an explosive failed to detonate and landed in the seat beside Ford. It did not go off and he was not injured. Spielberg stated before production began that very few CGI effects would be used to maintain consistency with the other films. During filming significantly more CGI work was done than initially anticipated as in many cases it proved to be more practical. There ended up being a total of about 450 CGI shots in the film, with an estimated 30% of the film's shots containing CG matte paintings. Spielberg initially wanted brushstrokes to be visible on the paintings for added consistency with the previous films, but decided against it. The script also required a non-deforested jungle for a chase scene, but this would have been