The two sea reptiles that chase the Herd throughout the film are named Cretaceous and Maelstrom: Cretaceous, a Metriorhynchus, is the purple crocodilian, while Maelstrom, the stout green reptile, is a Globidens. There was initially going to be a third predator, who appeared in some early designs as a small axolotl-like creature, but it was cut out. The back story for the villains is that they were frozen millions of years ago and kept in suspended movement.
The flashback in the movie was originally going to focus on Manny's conflict with his first family. However, Queen Latifah pitched the idea of the flashback in the film to center more on Ellie's origins.
The species of deer shown in the crowds is based off two different species of extinct deer: Hoplitomeryx, which had a distinctive horn on its nose, and Megaloceros Savini, which was a smaller species of Irish Elk known for its long antlers.
As an additional marketing ploy a special "anti-cell" spot was created with Sid complaining to the audience about a ringing cellular phone. The same was done for Brother Bear (2003), Robots (2005) and I, Robot (2004).
Surprisingly, animals similar to the horned beavers did exist. Ceratogaulus was a horned rodent, with the horns likely used for defence. However, it was not closely related to beavers, belonging to a separate and now-extinct family, and lacked the large, flat tail which it has in the movie. It more closely resembled a marmot or gopher.
The following were cut from the film: Originally a crisis would've erupted at the boat, as a vulture would've refused animals who did not have mates entry onto the boat (obviously taking the "ark" parallel further). A third reptile was going to appear alongside Cretaceous and Maelstrom. Originally the film was a No Antagonist story, but the filmmakers felt they needed an antagonist with a face, thus the creation of Cretaceous and Maelstrom Scrat was originally going to officially join the group, but was ultimately delegated to his traditional outsider role. The scene between Sid's encounter with the Mini-Sloths and the geyser field originally was a travel montage of the group crossing various perils. The director found it boring and livened things up with the "Food, Glorious Food" number, married with the previous concept of the group crossing the perilous landscape. Originally Ellie would've helped the group cross the geyser field by climbing to a tree and telling them where to go, and this would've separated her from Manny, Sid and Diego, as opposed to their fight in the final film.
In the original 2002 film Stephen Root and Alan Tudyk have voiced so many minor characters especially two main characters such as Frank the Rhino and Lenny the Scimitar Toothed Jaguar in that film now they're both voicing one character at a time such as a male aardvark who has one son known James and Cholly the Chalicotherium both Root and Tudyk have not made an appearance in Ice Age: Dawn of the Dinosaurs (2009) although Tudyk alone appeared in Ice Age: Continental Drift (2012) originally Stephen Root alone was going to have a role in Ice Age: Collision Course (2016).
The trivia item below may give away important plot points.
The Lone Gunslinger Vulture is the second character in a Blue Sky Studios film to be a hidden villain the first film to have a character do something like that is Robots (2005) with Ratchet this means that the Lone Gunslinger Vulture is the secret tertiary antagonist.