There's something hilarious and awesome about Shirako using the enormous speakers on his car to get rid of a bug in the Swamp Realm.
In the Swamp Realm Monkey tells Pork Chop to stay in the groove. When they get caught by the vines Monkey tells him,
Monkey: You did not stay in the groove Pork Chop.
Pork Chop: (mimicking him) You did not stay in the groove Pork Chop.
When the drivers enter the Storm Realm, Lani states that she has a bad feeling about it. Gig responds with "computers don't have feelings".
After the drivers get out of the Swamp Realm Nolo says he's taking Tork down. Markie says, "How about you take on me?" Now think of the song, "Take On Me".
On the start of Speed of Silence there's a montage of the drivers getting ready for the next realm... and then there's a short scene of Monkey staring at Lani and her making a face.
After Taro narrowly escapes the drones and goes through the entire Water Realm again all the Metal Maniacs cheer for their friend. The most notable reaction is Porkchop's, as he lies down near Gig after being traumatized by the aforementioned realm. How does he cheer? He punches Gig of course!
Pork Chop has a stuffed animal named "Ms. Piggy".
Before the Metro Realm opens, everyone is sleeping. Monkey has a particularly funny dream, with him gently floating through the sky filled with mechanical crap. He sees Lani, who beckoned for him to come closer. As he does... the alarm goes off and she makes this comical face, with her eyes going in different directions and her mouth wide open. You have to see it to believe it.
Monkey's hilariously huge drink he has before the Metro Realm. Comes up later when he says he has to pee. Then, near the end of the realm, he straight up pisses in Tork's car. Tork let's him drive.
When Lani picks drivers for the realms Monkey gets picked. He estatic that she chose him and thinks that Lani thinks that he's a good driver. Pork Chops response?
Pork Chop: Maybe she hopes you won't come back.
In the Metro Realm Nolo's car is upside down. To try and get out of there he uses his Swamp Realm Accelecharger. It forms a track... on top of him, pinning him to the ground.
In the Pipeline Realm Pork Chop asks who won the race(between Mark and Tork). Kurt tells Lani to tell Pork Chop that he won the race (In the Realm).
Kurt: See if he'll believe it.
When Pork Chop and Monkey go in the Junk Realm to save the other drivers Lani tells them they can't. Monkey tells Pork Chop that Lani is worried about them. He then goes on about how heroic he is as he faces danger everyday.
And then there's the part where Monkey shows Porkchop the Drone Sweeper drivers expression.
We're driving Old Smoky! Porkchop's at the wheel! When we hit the Junk Realm, We'll make the Drones squeal!
One of the Sweeper drones gets smashed to bits and leaves behind something Monkey's been looking for...
Monkey: YOU GOT LEGS!!!
Sparky:EH-OH, EH-OH, EH-OH!!!
Also in the final movie, there's the fight with now evil Kadeem. As Markie runs over to hit Kadeem while he's on his back, Kadeem kicks him high into the air with his robot legs. It's just so funny seeing Markie go flying waaaaaay up into the air, waving his arms like an idiot.