Visible crew/equipment: During Batman's interrogation of the Joker, when he picks him up and slams him against the wall, for a very brief moment you can see the camera and the cameraman in the reflection of the mirror on the right. (01:29:10)
Visible crew/equipment: In opening scene of the aerial view of the building adjacent to the bank, you can see the reflection of the filming helicopter on the left side of the building. (00:01:10)
Visible crew/equipment: In the scene where the convoy is driving through the entrance of the tunnel you can see the black helicopter the film crew uses right behind the police helicopter. (01:15:15)
Visible crew/equipment: When the Joker gets on the bus, after blowing up the hospital, about halfway along inside the bus is a large camera set-up. It can't belong to Mike Engel's news crew as it is not only too large to be hand held or shoulder mounted (it is one of the IMAX cameras used to film a shot from within the bus that wasn't used in the final cut) but also has a thick black cloth draped over it for the cameraman to work beneath. Obviously not a camera used by any news crew. (01:48:00)
Visible crew/equipment: When the Joker places the smoke grenade in the bank manager's mouth, a wire or tube can be seen on the left side of his face. It's only visible in the shot when the string pulls the pin, as soon as he drives away in the bus.
Answer: The gun fires using compressed carbon dioxide as a propellant. The cable is wrapped in a coil around a motorized turbine within the gun. The pulley system in Batman's belt buckle allows him to reel himself in hands-free and still maintain equilibrium. There is a four-pronged grapple at the end of the cable. This is what is magnetized, creating an attraction between it and the monofilament cable. This ensures that the grapple will attach itself to the cable for a secure hold. This is why the magnet itself does not need to be especially strong to support any amount of weight. It also explains the relative ease with which it can be detached and its seemingly "magical" ability to wrap itself around various objects.
Phixius ★