- Development Gag: Shinobi, the third Paradox faction class, are old Chinese spies and mercenaries. Spies were initially a faction class during development, but were instead replaced with the Space Marauder class.
- Development Hell: The game was originally set for release in 2008, but it didn't actually get released until 2010. See What Could Have Been below for the reason why.
- Name's the Same: "Jimmy Changa" is one of the suggested phrases for the chat, suggesting that Jimmy Changa was the name of an NPC who never saw the light of day. Interestingly, Jimmy Changa is the name of a LEGO Soccer Mania character based on the LEGO Adventurers line. While it's possible that the LEGO Universe Jimmy Changa might have been intended to be the same Jimmy Changa as the one in LEGO Soccer Mania, since we have no confirmation on the subject, it's most likely an unrelated coincidence.
- Some of LEGO Island's more cynical fans might argue that the LEGO Universe Sky Lane is not intended to be the same character as the Island Xtreme Stunts Sky Lane, and the fact that they share the same name is just coincidence. Many others, however, believe that they are the same character and it's not just Name's the Same.
- Recycled Script: The unreleased player-versus-player LEGO Kingdoms "Captures the Princess" minigame would have been a recycled version of an earlier Forbidden Valley Siege minigame revolving around pirates versus ninja.
- Screwed by the Network: Despite reportedly having over two million players, LEGO cancelled all future updates in November 2011 and shut the game down for good in late January 2012. Nobody knows the exact reasons why LEGO cancelled it, but the fact that LEGO is now developing two new MMO games makes one suspicious that LEGO did not want LEGO Universe in the way...
- Troubled Production: LEGO Universe was developed in a very trial-and-error sort of way, because LEGO representitives didn't have a clear idea of what they wanted, only guidelines for what they wouldn't be okay with. Add in some high demands from the parent company (such as a condition in the contract that the game have zero bugs upon release) and that makes for a prolonged development cycle.
- What Could Have Been: The entire game was redesigned in late 2009, nearly from scratch. When compared with most other LEGO games, the early design was Lighter and Softer then average, and the redesigned game Darker and Edgier.
- The redesigned darker game was also made easier. A common early complaint was that the game was too easy and too short.
- Before LEGO Universe was cancelled, the next update would have featured the return of Frostburgh and the release of the Fire Temple, complete with a boss battle against Lord Garmadon himself. Other worlds in the works include Ninjago-themed properties, a Ninjago Earth Gauntlet, two other Ninjago dungeons themed around ice and lightning, respectively, and an entire world based on LEGO Kingdoms, complete with a recycled PVP map from the game's early development days. The final trunk build of LEGO Universe showed other soon-to-be-released features, such as vendor dialogue and customizable hair options. And all this will never see the light of day because LEGO Universe got Screwed by the Network.
- Johnny Thunder almost got a design overhaul, but fan backlash resulted in a more faithful look with very few differences from his original one (he wears a patch on his left arm's coat, and his pants have more detail).
- The Summoner's valiant weapon was originally going to be a whip, since it reminds people of animal trainers, but they quickly decided against it; instead, they changed it into a wing-shaped Whip Sword style cat-o-nine-tail on a shepherd's crook.
- Why Fandom Can't Have Nice Things: It's been reported that one of the factors for the game's shut-down was because it was just too expensive to moderate all user creations to stop users crafting obscene items in a game that was meant to be all-ages.
Trivia / LEGO Universe