If you fly far enough in one direction without entering hyperspace, you'll eventually appear on the other side of the system you are currently in. Hostile ships, auto-pilot and escorts will act as though you were still on the side you were initially on. This is useful landing on blockaded planets.
If you get Ion Cannons by capturing a ship or by purchasing the Manticore, they are always legal, even though they are often found on Pirate vessels and legal ones are supposed to be found only on Federation ships.
Cats, from the game Zero Wing, appears in Escape Velocity Nova flying a red Leviathan. Hail him and the normal Leviathan picture will be replaced with a picture of him. Send him a greetings and he will respond with his infamous "All your base are belong to us" line. Also, attacking him will cause him to shout "For Great Justice!" He has extra weapons, such as Pirate Viper Bays, which you will have if you capture and use him as your own ship. He won't stay red if captured, however.
Create a new pilot with the name 'kenny' (not strict play), and proceed to play the game like normal. Any time you are killed, the status window (on the main menu) shows 'Oh my God! You killed Kenny!'
Sometimes you will come across a Polaris Zephyr named Shade of Blue. He was the beta tester who named the ship he flies. He has extra weapons that the normal Zephyr doesn't have, such as a 200mm Rail Gun. If you capture him, he will stay blue. You can then fly around and impress your friends with your blue Zephyr.
All of the ATMOS crew, as well as several Ambrosia employees, and Matt Burch are in the game as personalities.
After you beat one of the major storylines, there will be 4 new planets in north-western space. These four systems belong to some of the ATMOS developers, and can be found one jump up and one jump to the right of South Manchester