Conductor Red Rock (actor Eddy Waller) tells bad guy Rick Madden (actor Anthony Caruso) that Engineer Casey Jones (actor Alan Hale) is "one of the best Hoggers". This is old railroad slang. Heavy locomotives were nicknamed "Hogs", hence the engineer would be called the Hogger. It's unusual for Red Rock to call Casey Jones by this name, because many engineers considered the term "Hogger" to be disrespectful.
The name of one of the outlaws, Harry Longbaugh, is also the real name of the Sundance Kid.