Teen Titans (2003)

Employee of the Month - S4-E6

Trivia: The emerging of the Nufu Source's protective chamber is of course a spoof on the unearthing of the huge cryogenic chamber in the movie Akira.

X - S3-E2

Trivia: Red X pulls on Robin's mask, which pulls the flesh and skin around his eyes along with it as if it was glued on, and lets it snap back into place. In the comics, Dick Grayson (at least as Nightwing) indeed uses an adhesive named spirit gum to keep the mask on his face.

The End (2) - S4-E13

Trivia: While the Titans fight their own evil sides summoned by Trigon, the evil Cyborg taunts the good Cyborg about having no mother. As a matter of fact, in the mainstream comic series Cyborg's mother died because of a botched experiment by his father, which summoned an interdimensional monster. It was also on that day that Cyborg received his cybernetic prosthetics due to injuries the monster had inflicted on him.

The Beast Within - S3-E9

Trivia: When Beast Boy flips through the channels, we can catch a short glimpse of a car company advertisement which uses Adonis' logo; and if you look closely, you can see that several parts of the car on offer match parts on Adonis' battlesuit. My guess is that Adonis must have some connection to the car manufacturer in question and uses the production facilities and spare car parts to build his armor.