We can't forget the scene when Kaneda and his pals were at the police station. It opens with an Officer looking through files with a picture of Kaneda looking angry like he usually does. Then he put the file down and Kaneda, right in front of him has a goofy smile on his face. Then we see this exchange:
Officer A: All right, the story is, you and your friends went out at night on your bikes to visit your dying mother, and then another bunch of biker hooligans, called the Clowns, attacked you. They hurt your friend, you lost your temper, and that's why eight of these Clowns, your attackers, are now in the hospital. And that is the truth? (Officer B looks through files of recently brought criminals and a picture of Kei appears on his current page. Kaneda looks over at that picture)
Kaneda: Wowee! She's sure hot.
Officer B: Hey! This is confidential! (Kaneda chuckles, going back to his seat)
Officer A: And how's your mother doing?
Kaneda: Fortunately the worst is over. She cleared the hump.
Officer A: She cleared the hump, huh? What's next, a triathlon?
(Kaneda and a few of his friends laugh)
(Incidentally, Kaneda's inability to tell a convincing lie is why the police decide his group wasn't responsible for the revolutionary incident; they believe the real perps have got to be much more clever than that.)
The bar scene where Yamagata & Kai run into Tetsuo after his escape:
[Tetsuo crouching on top of some rubble, laughing to himself]
Yamagata: It's Tetsuo...
Kai: Why are you here...? You did this didn't you!?
Tetsuo: Look who's here. [extends out hand, full of pills] Wanna pop one?
Yamagata: WHAAAAT the hell are you talking about!? You look like a damn crack head!!
During the scene at the temporary police station in the gym, one guy busts out of an interrogation room, pursued by several cops, and pulls the pin on a hand grenade while screaming a "Facing the Bullets" One-Liner. Mass "Oh, Crap!" ensues with everyone scrambling to get away... and the grenade fizzles out, followed immediately by a horde of angry police officers tackling the guy. In the background he can then be seen having the shit kicked out of him.
About five minutes later, as the main characters are walking away, the grenade seems to finally go off at the gym in the background.
During one of the school scenes, the whole gang is sitting in class but the teacher appears to have not shown up, which leads to this:
Yamagata: But what about my burning desire to learn a vocation and contribute to society?
The anime briefly goes into Life of Brian territory after Tetsuo makes the projectile fired by the tank explode in mid-air. One guy climbs onto a car and proclaims Tetsuo to be Akira, only to be followed an instant later by another guy who declares Tetsuo to be "a false messiah." The only thing missing from that scene is the second guy calling Tetsuo "a very naughty boy."
First guy: Look! It's Lord Akira!
Second guy (also climbs onto the car, to stand next to the first one): Don't be fooled! This isn't the rapture, he's a false messiah!
First guy: Oh shut up! (pushes the second guy off the car)
In the manga, virtually every exchange involving Kaneda and Kaisuke qualifies.
A classic one: When Kaneda returns after disintegrating in the explosion of Neo-Tokyo, he and Kei spot each other across a crowd of refugees and run to meet each other, with Kaneda reaching out to catch somebody flying into his arms - only to discover it's actually Kaisuke, who jumped in between Kaneda and Kei in his excitement. Of course, despite Kaneda being less-than-impressed, Kaisuke doesn't take the hint and Kaneda winds up watching Kei longingly over his shoulder for the duration of the scene, since Kaisuke doesn't let go.
Shortly after this, Kaisuke takes Kaneda to meet his new friend Joker, and gives a passionate speech about rallying together to defeat Tetsuo, who has become the power-mad mutant overlord of Neo-Tokyo. Kaneda announces that, "I completely agree. But first..."
After thieving a couple of Joker's bikes to retrieve Kei on Miyako's orders, Kaneda and Kaisuke find themselves in trouble with a guy quite a bit larger than them and his not-so-happy-looking friends. Joker tells them they'd better pay him back, and as Kaisuke sputters for a response, Kaneda places a hand on his shoulder and gently tells him (before taking off running in the other direction):
Kaneda: I have to go.
A later bit with Kaneda and Kaisuke has both of them attempting to escape a tidal wave through a sewer as a result of Tetsuo destroying a good chunk of the moon, both on Kaneda's bike. Kaisuke comments that the bike won't be fast enough with so much weight on it, prompting the following response from Kaneda: