Instead of a WWI era helmet as possessed by the Gun Automaton, the Rocket Automaton appears to wear an American Civil War kepi.
Upon destruction, multiple fragments of the same part can be seen scattered around the machine's base. An odd result of this is that several head pieces can be found, supposedly belonging to a single automaton. This can also be applied to the Gun Automaton.
The Rocket Automaton is Columbia's variant of the Grenade Launcher Turrets from BioShock and BioShock 2.