Part of what makes the DUPLO aliens so hilarious is how they're essentially small children trying to join in the fun, but the film treats their unintentional destruction like something straight out of a Roland Emmerich film.
Batman throws a batarang at a DUPLO alien, which harmlessly bounces off of it. The subsequent exchange sounds exactly like two children at play arguing (mostly because that's what it is).
DUPLO: Missed me! Batman: (stomps his foot) No, I didn't!
In the same vein, Metalbeard tries shooting a DUPLO alien with a laser blaster. It eats the lasers and then this exchange happens, with Metalbeard sounding exactly like how a little girl's older brother would react to this;
DUPLO: I eat lasers!
Metalbeard: That's impossible!
When the Justice League are leaving on their ship, they're bringing along Lex Luthor... in a cage.
Emmet remains cheerful as ever despite living in the LEGO equivalent of a post-apocalyptic wasteland.
Emmet:[casually] Two coffees please! One black, one with just a touch of cream and 25 sugars.
There is a "Tween Dream" remix of "Everything Is Awesome", which plays as Emmet cheerfully strolls through Apocalypseburg.
The fact that Emmet's smartphone apparently has nothing but "Everything Is Awesome" remixes.
"WE DON'T SERVE DECAF!"
Surfer Dave becomes Chainsaw Dave in Apocalypseburg, and later Purgatory Dave during Armamageddon.
Emmet passes a group of guys getting into a brawl over which actor is the better James Bond.
Emmet cheerily observes that "Everything Is Awesome" really upsets Lucy, who immediately tries to deny it, adding a Death Glare and crushing her coffee cup.
Lucy trying to teach Emmet how to be brooding by having him practice saying, "War hardens the heart," over and over.
Emmet's dream house includes a spacious basement with trampolines, monkey bars, and a room full of giant toasters popping out both toast and waffles (as shown here). Why? "So you can have toast or waffles at any time!"
Lucy tries to convince Emmet to change with the times:
Lucy: We need to be tough and battle ready! Emmet: Yeah, I get it. That's why I've cultivated a totally hard-edged side that's super tough and- LOOK, LOOK, A SHOOTING STAR! Make a wish! (happy gasp)
Emmet gave their Mad Max-style vehicle turn signals of all things.
Likely a Call-Back to The Instructions from the beginning of the first movie: "Always use turn signals".
Unikitty accidentally fires a flare reading "Happy New Year" that Batman sees. After she fires a corrected one, it cuts to Batman and Alfred singing "Auld Lang Syne" together before they notice the new one.
Emmet: Hang on to your fronds, Planty! We're going... to save... Lucy! (Cue Aside Glance) And all the other people who were captured.
Sweet Mayhem taking the captured Master Builders to the "Systar System":
Master Builders: Whooooa! Lucy: No "whoa's!" Don't give her the satisfaction of whoa-ing this! Master Builders: Oooh! Lucy: That's even worse! Master Builders: Aaah! Lucy: STOP IT!
While on Mayhem's ship, Lucy sneaks a star projectile to use for later, but awakens it. The little guy cheers, "Hello!" When Mayhem grows suspicious and wonders, "What was that?" Lucy tries to cover by claiming, "I said, Heeeh-low!" The way her voice cracks when she imitates the star projectile's "hello" is what seals it!
The Master Builders meet Queen Watevra Wa'Nabi, a being that can take the form of anything, who was currently resembling a horse. She offers to take a more appealing form... which turns out to be a three-eyed octopus. Batman has to tell her that the horse was much better.
Queen Watevra Wa'Nabi singing an over-the-top song about how not evil she is... and the subsequent revelation that she really isn't evil, she and her subordinates are just terrible at communicating. The background singers repeat "not evil, not evil" in the background, which is so over the top it adds to the comedy.
Sweet Mayhem: The queen sang a whole song about how not evil she was! Lucy: That was the truth!? You guys are terrible communicators!
Queen Watevra asks Benny if he likes spaceships, cause she thinks they are great.
The reveal they're not actually evil and instead were trying to speak dark and gritty like the setting Apocalypseburg is going for and it's not working ends up making the song come out as her trying to spell out the truth as bluntly as possible...and being misunderstood anyway.
Benny's feelings on Queen Watevra's song.
Benny: My favorite part was the spaceship part! Also no other part, just the spaceship part.
Rex Dangervest explains how dangerous the Systar System is... while Emmet is too busy giving a raptor a tummy rub.
Rexs raptors all being named after 1980s action stars (Rocky, Conner, Ripley, etc.), with the exception of the last one, simply dubbed the other one.
Rex's Insane Troll Logic when he tries to convince Emmet that she is brainwashed, especially the way he says it.
Rex: And you can't wash the brain without washing the hair that's on top of that brain, it's basic science.
Watevra's Reverse Psychology song to Batman to get him to agree to marry her. What makes it hilarious is Batman's overdramatic "Waaaaaiiiit!" at the end, and the camera zooms out to show him slowly knee-sliding down to the other side of the table and the Queen.
Lucy: Did you draw stubble dots on your face? Emmet: What? No. (wipes his chin, smearing the ink on his face)
Becomes a little Harsher in Hindsight because Rex did something similar during his 'transformation'.
Batman's introduction at the wedding. While Ice Cream Cone announces everyone else* (all the individual members of both wedding parties, and Queen Watevera Wa'Nabi) politely, he announces Batman in an unimpressed, deadpan manner, as if he's just noticed that Batman is there. Then Batman makes his entrance...
Batman:COMMITMENT!! *Spins an electric guitar, whilst bats fly around and flames shoot up behind him*
Lucy's utterly deadpan reaction upon learning what causes Armamageddon.
Mom: Close to childbirth. Very close to the pain of childbirth.
Gandalf is one of the first to be seen falling into the abyss, framed to look just like his Heroic Sacrifice from The Lord of the Rings. Bonus gag after with the Sewer Babies on a platform which goes into the abyss, just like the orcs.
Right in the middle of one scene around halfway through, it is randomly interrupted by an animated 'intermission' card, complete with the talking snacks (represented by Banarnar, Ice Cream Cone, and Chocolate Bar) singing "Let's All Go To The Lobby". An animated Unikitty appears, and she pounces upon Chocolate Bar and takes a bite out of him, causing him to briefly scream before cutting back to the action.
Trailers and Promotional Material
After just 2 seconds: "A lifetime has passed since the horrific events of Taco Tuesday." If you haven't seen the first LEGO Movie, this line can come off as extremely funny out of context.
One of the teaser trailers on YouTube begins by acknowledging how catchy "Everything is Awesome" was. Then it begins extolling how obnoxiously catchy what appears to be the main song for the sequel (literally called "Catchy Song" very meta). The song plays and you expect the teaser to end so you can get to your actual video. But weirdly enough it keeps looping the same 10ish seconds (literally singing "this song is gonna get stuck inside your head!"). You look at the run time for the teaser. Turns out it runs for 5 HOURS! They really were not kidding when they promised an obnoxiously catchy song that would play so many times that you will never forget it! It's weirdly hilarious because the teaser appears to display the characters getting tortured/hypnotized with the song being played on repeat and the ad ends up putting the viewer through the exact same thing (assuming you don't skip or pause.)
There is now a 10-hour-long version that can be looked up in the search (Or just click here). It was posted a few days before the movie's release, and begins and ends the same way as the 5-hour YouTube ad version.
Emmet's Holiday Party
Emmet can somehow tell it's Christmas time even after the apocalypse.
Unikitty eats confetti thrown over the ice rink. She ends up barfing it on the Christmas tree.
Unikitty: My tummy's a little rumbly! (vomits the glitter she ate over some of the tree's branches) Yaaayyy!
Later, she goes Ultrakatty when the Systar ship lands, but when no fight ends up occurring, she finds herself unable to hold herself up on the ice.
Batman is displeased with Alfred's gift.
Batman: Alfred, this sweater only has eight abs! Not cool, bro. Alfred: But sir... Batman: 'Nog me!