Bowdaar: Just as Chewbacca was sometimes called "Chewie", so is Bowdaar called "Bowie". This is used in-game at a few points, but the nickname is so obvious it was in use before release.
Many people critical of the game have taken to calling it "TORtanic", joking how the game didn't live up to its expected status as a World of Warcraft-killer despite its huge budget and hype, similar to the disaster that befell the HMS Titanic.
The Esseles, the first flashpoint available to Republic players, is affectionately known by several monickers, including "the Glitch-sles", "the Bugboat", and "the Cheer-sles" due to the many Good Bad Bug-laden cutscenes.
Fountain of Expies: Each class is specifically modeled off a popular Star Wars character. Wanna Luke Skywalker? Play a Jedi Knight. Wanna Han Solo? Play a smuggler. Wanna be Boba Fett? Play a bounty hunter. Each class was specifically inspired by a character or set of characters in the films, and much of the artwork and designs are evocative of them. (The Bounty Hunter and Trooper design, for example). The Dark Side Jedi Knight on the other hand very nearly quotes some of Anakin's lines. The only class that doesn't have a direct source of inspiration is the Imperial Agent, who instead represents the Imperial officers in the movies.
This is perhaps most evident in the Sith classes: the Juggernaut is based on Darth Vader, the Marauder on Asajj Ventress, the Sorcerer on Darth Sidious, and the Assassin on Darth Maul.
Jindo Kraay, a boss from the False Emperor Flashpoint, is an Expy of Jango Fett.
For a non-Star Wars example, the Female Republic Trooper is essentially FemShep in the Star Wars Universe. Both characters even share the same voice actor.
This isn't just the classes; companions are designed to channel Star Wars tropes like the Big Aliens and protocol and astromech Droids. Even the ships resemble starships from the movies. And then we get to the non-Star Wars examples...
Alternatively, the six player classes are expies of the main characters in media set during the Great Galactic War, some of whom are also in the game.
The Sith Warrior is Darth Malgus, especially if a Juggernaut and/or a dark side male romancing Vette.
The Sith Inquisitor is Darth Thanaton, especially if a Sorcerer. Their similarities make their feud more poignant.
According to Word of God, there were originally going to bethree factions: Republic, Sith Empire, and Underworld. And before that, a developer said that they were going to have Voss Mystics as the third faction, so that's two factions that didn't pan out. They are focusing on creating more content for the iconic Republic and Empire classes, but have left open the idea of adding classes post-release.
Originally, there was going to be possible for players to permanently lose their companions. Due to the complaints from testers who figured it would be a case of Like You Would Really Do It (and assuming that paying players would make the same error in judgement), this feature was removed, as the goal of the game is to "be fun" first and foremost.
Existing sound files suggest that same-sex romances were originally planned for some companions. Three lines of Quinn's were found, apparently with identical dialogue to his romance with a female Warrior.
Before settling with the "Jedi Sage", it was originally called the "Jedi Wizard". Fan reactions were mostly negative and Bioware held poll to see how it should be named. The "Jedi Sage" got the most votes, followed by the "Jedi Adept", the "Jedi Seer" and the "Jedi Wizard" got the least votes.