Knock on wood! (taps on branch)note is a 1941 short cartoon released on June 7th, and the first solo short of Walter Lantz's most famous character, Woody Woodpecker, even though it is not his first appearance (that belongs to the Andy Panda short "Knock Knock").The short begins with a tune conducted to the rhythm of Woody's laugh, all while panning across the opening titles, not to mention a tree pecked full of large holes, courtesy of our hero. Woody literally bursts onto the screen, delivering his iconic "Guess Who?", followed up with his famous Annoying Laugh. After singing the opening song (quoted above), an annoyed owl causes him to ram into the tree and fall into a hallicinogenic daze, with the local Woodland Creatures commenting on Woody's insanity. A challenge or two later from them, and Woody ends up ramming himself into a petrified tree, dazing himself to where he decides he really is crazy, and goes off to see the local psychiatrist, Dr. Horace N. Buggy. It doesn't take long for the audience to realize that Mr. Buggy is just as crazy as Woody, if not more. Regardless, Woody plays along with the doctors shenanigans, until the short ends with Woody flying out of the doctor's office—and into the theater where the cartoon is playing! The Doctor promptly goes looney, while Woody annoys the audience member he's sitting next to enough to where he slams the seat into Woody, prompting his screams of help as the cartoon closes.
- Annoying Laugh: Take a wild guess who does this.
- Bragging Theme Tune: Woody's opening song.
- Captain Ersatz: It's really obvious in this early short that Woody was meant to be a Bugs Bunny and Daffy Duck knockoff. He even calls Dr. Buggy "Doc" at one point!
- Character Title: The short was originally just called Woody Woodpecker, but some prefer calling it by it's Castle Films reissue title for convenience.
- Completely Different Title: The Castle Films home movie rental release renamed the film The Cracked Nut so that people didn't confuse the generically named cartoon with being just any Woody Woodpecker cartoon, as opposed to being his solo debut. The official DVD release restores the original titles.
- Deadpan Snarker: Woody when a squirrel comments he has some screws loose.Woody (in mocking tone): "Oh, so i got some screws loose!"
- Digital Destruction: The official DVD print has some issues with DVNR, and even some nasty digital compression in a few frames.
- Early Installment Weirdness: Woody's design looks nothing like he does from Barber of Seville and onward, and he has none of the outright malicious tendencies he has in the Culhane and Lundy eras, being an unmotivated heckler instead.
- Mad Hatter: Woody, in his opening ditty.
- No Fourth Wall: The ending—it is not an example of Born in the Theatre however, as the audience is still set in a cartoon universe, and not our own.
- Not So Different: Woody and the Doctor.
- Off Model: Typical of the early Woody shorts, Woody would often go through this—there are some shots where he does have teeth, and some where he curiously doesn't!
- Porky Pig Pronunciation
- Punny Name: Dr. Horace N. Buggy. If you honestly don't get the pun, it's a play on "Horse and Buggy".
- Ridiculously Cute Critter: The squirrels Woody encounters.
- Screwy Squirrel: Woody, in full force here.
- Wheel o' Feet: Woody does this when he prepares for take-off.
- Woodland Creatures: The forest animals Woody meets early on.