doesn't matter what the prop person told him, when you handle a firearm its YOUR responsibility to prove (or ACTS) the firearm and make sure it is safe, also just by looking in the cylinder you would see the front of the bullet and realize that it wasn't a blank but a real bullet
All gunowners and users are taught this, and almost all of us follow this
Assume every firearm is loaded, Control the muzzle direction at all times
Trigger finger must be kept off the trigger and out of the trigger guard.
See that the firearm is unloaded