* DevelopmentGag: 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.
* DevelopmentHell: The game was originally set for release in 2008, but it didn't actually get released until 2010. See WhatCouldHaveBeen below for the reason why.
* RecycledScript: The [[WhatCouldHaveBeen unreleased]] player-versus-player [[Toys/LEGOCastle LEGO Kingdoms]] "Captures the Princess" minigame would have been a recycled version of an earlier Forbidden Valley Siege minigame revolving around pirates versus ninja.
* ScrewedByTheNetwork: 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...
* TroubledProduction: ''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.
* WhatCouldHaveBeen: The entire game was redesigned in late 2009, nearly from scratch. When compared with most other LEGO games, the early design was LighterAndSofter then average, and the redesigned game DarkerAndEdgier.
** The redesigned darker game was also made ''easier''. A common early complaint was that the game was [[ItsEasySoItSucks too easy]] and [[ItsShortSoItSucks too short]].
** Before ''LEGO Universe'' was cancelled, the next update would have featured the return of Frostburgh and the release of the [[WesternAnimation/{{Ninjago}} 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 [[Toys/LEGOCastle LEGO Kingdoms]], complete with a [[RecycledScript 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 ScrewedByTheNetwork.
** [[Toys/LEGOAdventurers 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 [[WhipOfDominance a whip since it reminds people of animal trainers]], but they quickly decided against it; [[HypocriticalHumor instead, they changed it into a wing-shaped]] {{Whip Sword}} style [[JerkWithAHeartOfGold cat-o-nine-tail on a shepherd's crook.]]
* WhyFandomCantHaveNiceThings: 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 [[VideoGamePerversityPotential crafting obscene items]] in a game that was meant to be all-ages.