- French Narrator
- Johnny Elaine
- Old Man Winter (mentioned)
- Gary the Snail
- SpongeBob SquarePants
- Jimmy Gus
- Snow fish
- Snow whale
- Kid fish
- Snow mermaid
- Eugene H. Krabs
- Mrs. Puff
- Sheldon J. Plankton
- Patrick Star
- Daydream Patrick (mentioned)
- Squidward Tentacles
- Meteorologist (heard only)
An iceberg travels across the surface of the ocean and stops over Bikini Atoll, causing it to snow underwater in Bikini Bottom. Everyone notices and starts to have fun in the snow, while SpongeBob and Patrick decide to have a snowball fight. Meanwhile, Squidward is relaxing at his house, sitting near a fire and drinking a cup of tea. He hears the sounds of SpongeBob and Patrick's snowfort building and tells them to quiet down. They try to convince him to come out and play with them, both trying to get him on their own side, but Squidward shoots both of them down.
Squidward decides that, as entertainment, he will watch them fight, hoping they will get hurt. SpongeBob and Patrick realize that snowball fights are for children, and they sign a peace treaty. Squidward tries to convince them to continue for his entertainment, but repeatedly gets hit with a snowball by Patrick as a result. He then decides to throw a snowball and misses both of them. SpongeBob and Patrick then proceed to duck behind their fort and mercilessly begin to pelt Squidward with snowballs. Afterwards, a frustrated Squidward proceeds to throw a snowball and hits SpongeBob right in the face. He soon becomes exhilarated and begins relentlessly pelting SpongeBob and Patrick with more snowballs. After being hit by a snowball containing his clarinet, SpongeBob and Patrick decide that Squidward is taking the snowball fight far too seriously and sneak off.
When Squidward notices that the snowballs have "stopped falling," Squidward becomes paranoid and riled-up, realizes his fort is too small, and decides to make his fort bigger and eventually builds it to the size of a tower. Squidward continues to throw snowballs as an overhead tree branch keeps dropping snow on his head that he believes are snowballs being thrown by SpongeBob and Patrick. Meanwhile, the two of them relax in the pineapple, watching TV while drinking hot chocolate and eating popcorn.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Wonderland of Snow - Terry Day [title card]
‣ America, A Dream Comes True - Gregor F. Narholz [opening]
‣ The Jolly Sleighride - Ib Glindemann [Bikini Bottom covered in snow]
‣ Danger Zone - Mike Sunderland ["This is serious, SpongeBob."]
‣ Harp Ding - Nicolas Carr ["Snowball fight?"]
‣ Vibe Q Sting - Nicolas Carr [Patrick trying to make a snowball]
‣ Battle Begins - Nicolas Carr [SpongeBob and Patrick glare at each other]
‣ Romantic Waltz - Geoffrey Herman [Squidward relaxing]
‣ The Merry March (a) - Paddy Kingsland [SpongeBob and Patrick building forts]
‣ Tomfoolery - David Snell [Patrick choking on snow]
‣ Comic Walk - Sidney Torch ["Snowball fights are for immature children."]
‣ Vibe Q Sting - Nicolas Carr ["Hmm..."]
‣ Tympup (a) - Sammy Burdson, John Charles Fiddy [SpongeBob and Patrick shake hands]
‣ Comic Walk - Sidney Torch [peace treaty]
‣ Twelfth Street Rag - Sage Guyton, Jeremy Wakefield [Squidward trying to start another snowball fight]
‣ Marshall Strength Link - David Snell [SpongeBob and Patrick throw snowballs at Squidward]
‣ Harp Ding - Nicolas Carr ["That was actually kind of exciting."]
‣ I Saw Three Ships 29 (c) - Richard A. Harvey ["I have never felt so live."]
‣ Earl's Revenge - Sage Guyton, Jeremy Wakefield [Squidward throwing snowballs]
‣ Vibe Sting - Nicolas Carr ["What's going on?"]
‣ Sponge Monger - Sage Guyton, Jeremy Wakefield [ending]
- "Snowball Effect" was ranked #20 during the Best Day Ever event on November 9–10, 2006.
- While it is Bikini Bottom's second actual snow day (the first is "Christmas Who?"), this episode marks SpongeBob and Patrick's second winter-based fun since "Survival of the Idiots."
- This episode marks the fourth appearance of snow, the first three being "Bubble Buddy," "Christmas Who?," and "Survival of the Idiots."
- Running gag: Squidward's fireplace is put out by a snowball that is thrown.
- When Squidward is sitting next to his fireplace, a replica of his head with moose antlers is seen hanging on a plaque on his wall. It is seen again in the SpongeBob SquarePants video game Battle for Bikini Bottom.
- A clip of this episode was shown in a 2006 LEGO SpongeBob commercial.
- When Patrick tries to make a snow angel, he only makes a circle.
- SpongeBob reuses the quote "Score one for the boys back home" from "Naughty Nautical Neighbors." He later uses it again in The SpongeBob SquarePants Movie video game.
- The scene where SpongeBob batters Patrick with a barrage of snowballs is rarely shown in Indonesia airings due to time constraints (much like other episodes, it is also paired with ads during its airing).
- This episode sometimes airs in December due to it being a snow-themed episode.
- This episode probably takes place after "Christmas Who?" since SpongeBob wears a Santa hat for part of the episode, which suggests that he was already familiar with Santa Claus at the time of this episode.
- This episode premiered on Nigel Planer's 49th birthday.
- In Arabic, this episode is called "معركة الثلوج" (maerakat alththuluj "mar-eh-kat ool-sul-oo-zhey"), which means "battle snow."
- Patrick's alias "Pink Menace" is a reference to the "Red Menace," a nickname for the Soviet Union that was popular during the Cold War.
- The title is a reference to the phrase "snowball effect," which means:
- Literally: The effect used in a cartoon when a skier is skiing and trips and falls and makes a snowball that grows bigger and bigger.
- Metaphorically: When a situation gets out of hand.
- "The Snowball Effect" is also the title of a famous short story by Katherine MacLean.
- Netflix and YTV mistook the title for "The Snowball Affect."
- When Squidward speaks about him being attacked in the rear, there is already a wall there and all he does is turn around, laugh, and pat the wall, but he is never seen building it.
- When Mrs. Puff blows the snow off her boatmobile and onto a nearby fish, the fish pops his head out and yells "Hey!," although his mouth doesn't move.
- When Squidward demonstrates his fort and how it should be used, and Patrick throws snowballs at him, his arm doesn't move.
- When SpongeBob is first seen with his fort, it is circular and shorter than him, but when the camera returns to SpongeBob, his fort has changed shape and is about as tall as him. Finally, when the camera returns to SpongeBob again, his fort returns to how it originally was.
- When Squidward drops his snowball after he refuses to be on neither Patrick or SpongeBob's side, the mark that he makes in the snow disappears when the camera pans out.
- When the camera shows Patrick laughing after hitting SpongeBob with a snowball, his fort is smooth. Before, it was full of bumps. Also, when Patrick comes upon the barrage of snowballs SpongeBob serves at him, his fort is bumpy again. Also, all the square snowballs he was seen with are gone.
- When a close-up of the DNA strand snowball Patrick made is shown, the sky is light blue instead of gray.
- When Squidward gets frustrated by Patrick's continuous snowball-throwing at him right after he builds his small fort, he attempts to throw back a snowball at Patrick but misses his shot. Instead, the snowball goes inside Squidward's house and puts out his fireplace. This would not have been possible because his house is behind him at the moment he throws the snowball.
- When Squidward builds his fort near the end of the episode, Patrick's house is not seen.
- At the end of the episode, the coral tree that drops snow onto Squidward's head had not been seen throughout the episode.