In the scene where Dug enters the Bronze-age village, a zebra pelt can be seen lying in the road. Although the reference may go over the heads of the American audience, it is obviously a pun on the British term "zebra crossing".
One of the commentators at the final match describes Dug's team as "Early Man united," a reference to the Manchester United football team in England. Goona's name is a play on "gooner," a slang term for fans of Arsenal - another English team and a long-standing rival of Manchester United.
The name of Queen Oofeefa is a play on FIFA( Fédération Internationale de Football Association), the organisation responsible for football's major international tournaments, notably the World Cup which commenced in 1930 and the Women's World Cup which commenced in 1991.
The gag where Dug, Goona and Hognob jump out of the window and their fall is broken by a roll of toilet paper was originally intended by Nick Park for inclusion in The Curse of the Were-Rabbit (2005), but he couldn't find a way of fitting it in.
In the end credits there are caving paintings on the wall of football playing cavemen. Among these painting can be seen several other characters from other Nick Park movies including the Were-Rabbit, Grommit and the Beady Eyed Penguin.
Miriam Margolyes, Timothy Spall, Mark Williams, and Eddie Redmayne have all played characters in the Harry Potter universe. Margolyes played Professor Sprout, Spall played Peter Pettigrew, Williams played Mr. Weasley, and Redmayne played Newt Scamander in Fantastic Beasts, the Harry Potter prequel series.