BFG: In a general sense, any gun above .50 caliber. However, High Road to Revenge features the Fw-206 Doppelganger, a single-engine aircraft equipped with a 75mm cannon adapted from a tank gun, touted as the largest gun ever fitted to a production aircraft. In Real Life, a number of aircraft on both sides of the war were fitted with tank guns, primarily for use in the ground-attack role. However, these were not terribly popular and all of them were large twin-engine aircraft, not a fighter-sized single-engine plane like the Doppelganger.
Could Have Been Messy: Unless they crash or were shot down close to the ground, pilots will always eject to safety and deploy their parachute once they're going down.
Cool Airship: The Pandora, mobile home base of the Fortune Hunters.
Cool Plane: The standard issue, default designs are pretty dull, but you can customize their appearance to invoke this.
Diesel Punk: Of the highest order. Art Deco prop planes and zeppelins mix it up with guided missiles and electroshock weapons.
Men of Sherwood: When you have wingmen (and in some missions, pilots from non-Fortune Hunter factions), they perform quite well. Obviously It's Up to You like most games, but they have excellent staying power and will almost always take out a few planes for you.
Flying Aircraft Carrier: Not exactly an aircraft carrier in the traditional sense, but Zeppelins do hold complements of airplanes.
Aerial torpedoes. A single missile able to take out an entire section of a zeppelin is on the fast track to cool, but they have several problems including being so slow they can be shot apart by enemies, a minimum deployment range and lack of a guidance system that makes them hard to aim, most missions not requiring a zeppelin to be destroyed, the method of firing at open broadside cannon ports being arguably easier, and the fact that you can't have many of them with you.
The Beeper-seeker missiles in single player. It's basically a guided missile system in which you first have to fire the tracking "beeper" at your target then fire the guided "seeker" missile, guided by a signal from the beeper. Despite how awesome the idea of a guided missile is, ditching the non-damaging beeper in favor of a high-explosive rocket is often the better choice.
Hero Killer: Inverted. The Blake Aviation Security firm preps to go on a pirate hunting mission with their new zeppelin, but it gets destroyed by the player in one mission, and in yet another mission you have to rescue BAS zeppelins from another band of pirates. The rest of the anti-pirate forces in the game suffer equally embarrassing losses against the very people they were hired to take down; the Hollywood Knights are beaten on their own soil.
Lovable Rogue: Nathan Zachary and to an extent the rest of the Fortune Hunters.
Neighborhood Friendly Sky Pirates: The Fortune Hunters are criminals, but their criminals acts are not necessarily as terroristic or harmful as they could be, and they actually do a handful of good things in the story, culminating in them saving New York City from the corrupt security firm Sacred Trust.
Point Defenseless: Inverted. Zeppelin turrets can brutalize the player if they are careless.
Simple Yet Awesome: High Explosive rockets. They produce a pretty purple-colored explosion that can take out just about anything in 1 or 2 hits.
War for Fun and Profit: One of the first acts of the Red Skull Legion involved escorting a zeppelin supposedly full of Mormon refugees from the Industrial States of America. It wasn't, but the ruse allowed the zeppelin-loaded with a small army of pirates-to slip past Utah's air defense network. Once inside, the Red Skulls seized control of an airport and stole the zeppelin carrier Moroni (later renamed Machiavelli). Then the Red Skulls repainted their planes in the colors of the Utah Air Militia and launched a series of raids into the People's Collective. Utah got blamed and the People's Collective launched a series of punitive expeditions. While the Collective and Utah were at each others throats the Red Skulls slipped away scot-free with a brand new carrier zeppelin and a cargo hold of loot. Ladies and Gentleman, there is a reason that Red Skull founder and leader Johnathon "Genghis" Khan is considered a Magnificent Bastard.
Weather Control Machine: One of Die Spinne's superweapons. It's mounted on one really, really big zeppelin battleship.
Wretched Hive: Arixo, a desert nation-state formed from the remnants of Arizona and New Mexico. Its vast desolate and lawless expanses makes it a natural haven for bandit activity.
Which is nothing compared to the pirate kingdom of Free Colorado.
Zeppelins from Another World: Somewhat appropriate considering the time period of the setting, but they were used far more than in real life.