Angry Birds Seasons is the second Angry Birds game to be released and it got a lot of unused content as seen below:
Unused Bird Wear
An unseen Bird Wear appears in the preview for the Bird Wears, it's the Scientist Bubbles costume. It isn't obtainable in the game by any sort. It could possibly be a beta design for Bubbles's Hulk Costume.
In the files, there is a sprite for a button of the episode Year Of The Goat that is not used in the game and was probably meant to be released on the start of 2015, since this was the latest Year Of The Goat and it uses the Classic Designs. While not used in the game, a Chinese Version of Angry Birds Classic features this episode fully playable.
Unused NamesThere are some names that weren't used and are different or placeholder name the developers made.
In the files, the assets for the Tropigal Paradise episode have the name ''Tropical Paradise'', a placeholder without the pig pun.
In the files, the assets for Invasion of the Egg Snatchers have the name ''Eggsfiles'', a initial name for the episode that uses a pun on ''X-Files'' but they probably didn't use this name because it doesn't make so much sense.