At the end of "A New Day", when Lee walks up to Clementine and Duck, Duck will describe a comic he read called "Super Dinosaur." This is a comic written by creator of The Walking Dead, Robert Kirkman.
Contributed by Tristan_Brown
There are unused icons in the game's data for episode one. These include a hammer, teapot, running icons, and a rag. The hammer and teapot were scrapped entirely, the running icons were cut out of episode one and put into episode two, and the rag was used in episode three instead.
Contributed by frankfrost2
Telltale hosted a pre-order contest for Mac and PC users, where the winner would appear as a survivor in-game, while four runner-ups would appear as zombies. Brie Rosenholm won the contest and appeared in "Around Every Corner" and "No Time Left". The four runner-ups appeared as zombies near the end of "No Time Left".
Contributed by SOGESNAKE
Doug once had his own subquest in early development, in which Lee had to knock the pole onto his brother while Doug attracted the walkers away with Kenny's truck. Lee had to cut the electricity before cutting the pole with a fire axe.
Contributed by Ben Paul
In chapter 4 of the third episode there's a bottle of Banang in the right cup holder. The inclusion of this drink is a running gag in most games developed by Telltale Games. It first appeared as a joke in "Sam and Max: Beyond Time and Space" as a powdered flavored drink with a funny name. Banang is possibly a parody of Tang, a fruit flavored drink sold worldwide.
Contributed by David
The character Doug is based off of Doug Tabacco, the IT specialist at Telltale Games. The appearance of Doug is based off of him as well as his behavior.
Contributed by Breakinggreens
In Episode 5: No Time Left, while in the room with the dead couple on the bed, talking to Kenny repeatedly will eventually cause Lee to walk over and face the player, and say "Randy Tudor. Good man. Damn fine man. Powerful 'stache. One of the greats."
Contributed by epicmickeyfan
In the game's files there are two unused character's.
One is named "Nick Stokes", who seems to be wearing a uniform with a badge. The badge also features a photo of the character Nick Stokes from CSI: Crime Scene Investigation.
The other is called "Jeff". Jeff is the only character who has the special walker texture.
Contributed by Ghost