True to form, Flash is the main exporter. Whenever bad guys are involved, it frequently turns into a Crowning Moment of Awesome as well. His treatment of Evil Black Canary is perhaps the best example.
At one point, Model Citizen, an Earth-Two telepath who is the evil version of Looker, tries to control his mind.
Model Citizen: You don't want to fight me, you want to help me.
Flash: I don't want to fight you, I want to (shakes off mind control) Hey, this is like the Jedi Mind Trick!
Model Citizen: *putting Flash back under mind control* This is not like the Jedi mind trick.
Flash: This is not like the Jedi mind trick.
Good Lex, especially when first visiting Earth-1. He ensures the Justice League is summoned by mock-threatening to blow up the world, and when they arrive, he has stripped naked to demonstrate he's not armed.
Superman: (Good Lex starts to stand up but Superman stops him): ...Pants.
Good Lex: *Looks down* ...Oh.
The cherry on top is the tone he uses, like "oh right, people wear those don't they".
What's the first thing he does upon arriving? Asks for directions.
Good Lex: (totally polite and friendly) Good morning. Would you be kind enough to direct me to the nearest police station?
Batman using the experimental teleporter to transport Flash to the Watchtower, and then stealing his pretzel.
Evil Jimmy Olsen. Just... Evil Jimmy Olsen.
The sly Mythology Gags of Good Lex calling him "Ultraman's Pal" and him having a signal watch that calls Ultraman to his aid.
When fighting Johnny Quick, Quick starts picking up bits of jagged debris and hurling them toward Flash at supersonic speeds. Not only does Flash catch every single piece, he REASSEMBLES them and tosses the repaired part to Quick. Cue "Bugger."
Flash picking up Scream Queen, running on water, and then he just puts her down in the water, and runs back.
Flash asking Wonder Woman why she even needs to keep the invisible jet if she can fly and then having Hal Jordan point out he drives a car in his civilian life.
Adding to that, when Flash finds out Diana brought the plane with her to their world by running into the wing at Super Speed head first. He flips around in the air and lands on his face.
Even more funny if you take into account this line from Justice League (which the movie was originally meant to be in-continuity):
Green Lantern's skittishness upon being charged with going to Earth-3 and cleaning up. "For all my power when it comes down to it I'm just a beat cop. There are rules, another dimension may be out of our jurisdiction."
Superwoman, after catching Batman when he chased her back to her own world, reviews some of the other worlds she could send him to:
Superwoman: Hmm, here's a world where humanity has mutated into hideous creatures of the night... No, you might like that.
Also a Fridge BrillianceContinuity Nod; there's several DC Comics Elseworlds stories that have Batman either fighting vampires or turning into a vampire. Furthermore, the general concept behind the Batman villain "Man-Bat", a humanoid bat, is that he was a man who admired bats and/or Batman so much he transformed himself into a hybrid of man and bat.