The studio originally wanted Benedict Cumberbatch to voice the Grinch using his natural voice, but Cumberbath felt that, since the rest of the cast is American, the Grinch should have an American accent.
When Cindy-Lou Who and her friend go up into the tree house, the baseball bat on which they ride as a platform has the name "Theodor" carved on it. Theodor Seuss Geisel, a.k.a. Dr. Seuss, wrote the Grinch book.
When asked if this movie was always the direction of the storybook, Benedict Cumberbatch stated: "You don't necessarily get the whole script. There's pitches all along the way and you know where it's going. But I did say quite early on I really want to know why he is the way he is. Maybe there is a reason behind that, that he's been hurt before. Why is he outside? Why is he green? Why does he live on his own in a mountain? What is all that about? The sort of motivational questions that a navel-gazing actor always asks. But you do need to make sense of characters. They can't just exist in a vacuum, even if they're animated characters in a family film."
In Meu Malvado Favorito 3 (2017), the oldest of Gru's girls, Margo, is seen wearing a t-shirt with this version of the Grinch on the front. Both are from Illumination Entertainment and this was clearly a nod to the upcoming movie. In Meu Malvado Favorito (2010), Margo had a Lorax shirt, teasing Illumination Entertainment's O Lorax, em Busca da Trúfula Perdida (2012), a fellow Dr. Seuss movie.
Pentatonix: singing "God Rest Ye Merry Gentlemen" when the choir was chasing the Grinch with Christmas carols.