Here's a couple I haven't seen anyone mention yet:

- Steven Universe: the episode "Last One Out of Beach City" has characters working on a puzzle that is 612 pieces and resembles the Battlefield on Skaia.

- Battle for Dream Island: the episode "🥚" (yes that's what it's called) of the show's 2nd season has Perfectly Generic Objects as one of the potential prizes on the prize wheel.

- Smiling Friends: The bar in the post credits scene of "The Magical Red Jewel (aka Tyler Gets Fired)" features several posters and clippings on the wall that are very blatant homages to Homestuck. Like a ridiculous amount lol.- Forsaken: Features Wayward Vagabond as an unlockable skin for one of its characters.