- The song Christmas Time Is Here starts earlier than in the 1966 to present version to allow the full song to be heard instead of fading out once Charlie Brown hits the tree. The dialogue was relaid and the start of the music was pushed back farther in the later version
- No sound effects when Snoopy throws Linus and Charlie Brown around.
- During the main title shot the sound effects are differently pitched, both the wobble of the tree and the plop of the snow, after Charlie Brown crashes.
- Snoopy throws Linus into a Coca Cola sign and the song fades out with "Christmastime..." repeated several times. The original sign was a standard Danger sign before being changed to the Coca Cola version. The early sign can be seen in the original CBS promo and for 1 frame in the Coca Cola version.
- Disproving rumors, the can that the characters throw snowballs at is NOT a Coca Cola can.
- Lucy does not make a whirling noise when she reacts to Charlie Brown‘s “THAT’S IT!” during the psychiatric booth scene. The background music also stops during this moment instead of continuing to play like in the present version.
- When Snoopy decorates his doghouse "Christmastime Is Here" continues to play instead of the more upbeat "Surfin' Snoopy". There are no zipping noises as Snoopy moves around decorating his doghouse. Charlie Brown is silent for 4 seconds while reading the flyer Snoopy hands him after mentioning “Find the true meaning of Christmas, win money, money, money!” then his voice from the Disneyland/Vista read-alongs is spliced in the soundtrack to exclaim “Lights and display contest! Oh no!” then quickly reverts back to Peter Robbins' voice for Sally’s list scene.
- When Charlie Brown is greeted as director, Snoopy's howling is shorter and sounds more realistic and wolf like.
- There's no music playing in the background during Charlie Brown’s director speech scene until the 'Linus and Lucy" dance.
- The shot of Schroeder listening for Charlie Brown to tell him to “set the mood” is a static shot of all the characters standing on stage where their dancing positions are. This causes an animation error once they start dancing again where Pig Pen only strums the bass two times instead of with the music. The present version has Schroeder sitting alone on a pink background.
- When Charlie Brown is explaining the roles to Frieda and Pig Pen, the full background can be seen causing the characters to be farther away from the screen and Pig Pen’s face is clean whenever he faces the screen.
- When Lucy gives "five good reasons" to Linus we don't see a close-up of her hand making a fist.
- There's no swooping noise when Lucy attempts to slug Snoopy and he doesn’t make a 'Blah" sound after licking Lucy.
- Snoopy's dish is white in the "Lunch Break" scene and the sound effects of him kicking it around are realistic clanking sounds instead of the later cartoon type noises. One frame is also rearranged in his sequence
- There’s no music during Lucy’s script girl scenes.
- When Lucy reacts to Charlie Brown and exclaims “I know when I’ve been insulted !” the full background can be seen and the characters are farther away from the screen. Charlie Brown's nose is also missing for a frame.
- The long shot of the characters dancing on stage is played for an additional time. In the 1966-present version, they're in their costumes in separate shots on a pink background.
- Lucy's fingers don't make a snapping sound when she likes the music.
- When Charlie Brown tries to find a tree Linus doesn't bang on the aluminum tree. Charlie Brown‘s reaction to the tiny tree is also very brief. We don’t see Linus when he says “Gee do they still make wooden Christmas trees?”
- The scene with Schroeder and Lucy goes as normal, but Schroeder doesn’t make a drum roll sound while spinning.
- There is no music in the background when Charlie Brown and Linus return with the tree.
- Linus' speech is intact and he doesn’t pick up his blanket in the full shot of the auditorium. This was reanimated in the later version resulting in a continuity error.
- Once Charlie Brown is eager to decorate the tree and heads home, there is no fade out to commercial (the shot also lasts several seconds longer due to this). It immediately cuts to Charlie Brown's shock of Snoopy winning first prize. Also, Charlie Brown's reaction to the award is slightly longer.
- When the kids decorate the tree the animation of them decorating it only plays once and Charlie Brown‘s reaction to it is brief.
- While the kids hum the “loo,loo, loo,” portion of the song and take a breath there’s no background error present where in the later version the characters in the back row overlap the rest of the characters in front of them for one frame.
- Charlie Brown blushes while singing and Snoopy sings like a human instead of making a howling motion. The mouths of all the characters were redrawn in the 1966 version to appear more natural.
- The song Hark The Herald Angels Sing does not fade out but concludes with an onscreen message saying "Merry Christmas from the people who bottle Coca Cola".
- There is no "The End" copyright screen, it was apparently added in 1966 after the studio realized that the special would be airing more than once.
- There's a spot afterwards where Charles Schulz thanks Coca-Cola for sponsoring "A Charlie Brown Christmas".
Besides the Paley Center for Media, the only way to access a print of the original version of the special is by acquiring a print from a private collector. Besides the two Coca Cola sponsor plugs, the entirety of the original version has never been made publicly available on the internet. It is doubtful this version will ever get a home media release.
UPDATE: An original print of the special was shared as an MKV to the Lost Media Wiki and is available on the Internet Archive. A comparison video with the two prints is available on YouTube and Vimeo.
Book: "A Charlie Brown Christmas: The Making of a Tradition"