Snoopy's noises and Woodstock's chirpings are taken by Bill Melendez's performances from earlier Peanuts animated productions from 1965 to 2000 (including movies, TV series and TV specials). Years later the same technique was used in Tom & Jerry (2021), where are featured archive recordings of William Hanna, who did all of the original screeches, yells, gasps, shrieks, howls and screams for Tom and Jerry heard in the original cartoons from 1942 to 1957.
The first theatrical Peanuts movie in 35 years, since Bon Voyage, Charlie Brown (and Don't Come Back!!) (1980).
Charles Schulz wanted to call his comic strip "Charlie Brown" (it had started out as "Good Ol' Charlie Brown"), but the editors were worried about legal action from people who had that name. It started publication as "Li'l Folks", but because that was too similar to the title of someone else's strip, his syndicate forced the title "Peanuts" on him. He hated the title (partly because it made people assume the character's name was Peanut) and didn't use it in any of the specials or movies, which were titled "Charlie Brown" or "Snoopy". This is the first "Peanuts" feature to carry that title.