Chickens in Pop 'till they drop! (all variants) had a different movement pattern that did not oscillate as much
Chickens in Double Trouble (all variants) would fly in from the sides instead of from above
Chickens in Chicken Geometry (all variants) are supposed to fly in quickly similarly to how they work on “Right Angles”
I noticed that the brighter pink shirts in waves like Chicken Geometry got replaced with the new brown shirt that appears on chapter 9
Comet Chase spawns more comets in general, for example the first wave has 25 comets instead of 20
Feels like chickens in Reinforcements move slower than they used to
UCO 3 lost the laser on some difficulties
Boss chickens in Attack of the Clones! are much larger than they were originally
Ship engine smoke spawns in the middle of the screen when the ship arrives in the final cutscene
It’s redundant in CIU but it would be nice if the checkered chickens (to indicate they hold coins) could come back in earlier waves, similarly wondering if the bronze/silver coins could return
Edition related nitpicks:
CI3 Easter had its own patterned eggs as well as a different reskin for regular and boss chickens
The cutscenes in CI3 Xmas used the regular CI3 theme