The festive instalment will feature Harry Potter star Michael Gambon and singer Katherine Jenkins in key roles.
Smith told USA Today: "I had great fun making [the episode] because obviously it was the middle of July and there's loads of fake snow. There's lots of snow, crackers and turkey, and that goes hand-in-hand with the spirit of The Doctor and Doctor Who."
He added that the special would focus heavily on The Doctor's own festive spirit.
"It's showcasing humans at their most open and giving and kind," he said. "It's everything The Doctor's about."
Smith also referred to his role on the sci-fi drama as "the greatest part I've ever played".
"What's so wonderful about playing The Doctor is it's all based on invention," he explained. "You're given this white canvas to invent and paint on, and he can be any colour. I really want to push the boundaries of this part into next year now and keep raising the bar."
The as-yet-untitled Doctor Who special will air on BBC One this Christmas.