Although "Friendship is Magic" is not officially canon with previous incarnations of the My Little Pony cartoons, Twilight Sparkle's mother closely resembles the unicorn Twilight from the first generation of the television show.
Pinkie Pie's full name is revealed to be Pinkamena Diane Pie.
Derpy Hooves, the fan-favorite pegasus with crazy eyes, can be seen briefly flying over Canterlot at 11:59 and twice in the audience at 12:11 and 12:19.
Two of the fillies Rarity designs a costume for are recolors of Applejack and Pinkie as fillies.
Friendship Report: The Mane Six learned everyone has a special connection with their friends long before they meet.