Henry is supposed to have no voice, but after his first quest from Jimmy to get the battery from Slick Dmitry (after giving the lighter to some guard) he made a vocal sound when nearly falling off a building, and not the breathing sounds.
At the end of of the chase of Dimitry in Jimmys first quest, Dimitry is got a headshot. At first you hear the shot, than explode his head. For real, the bullet is faster than sound. So the head should explode at first, and after that you should hear the sound of the gun.
When Henry opens the emergency exit on the airship, he nearly falls out and manages to hang on. At that altitude (high above the cloud layer), he would be sucked out and the entire compartment would decompress (the same as if you opened the door of an aeroplane in flight).
While chasing the Slick Dmitry on the roof in first Jimmy quest, Henry jumps the building via a sling rope; he first holds a black rope, but when he lands in the rubbish box in the street, the rope is pink.