Three songs from the show gained particular popularity as internet memes: "You Are a Pirate"; "Cooking by the Book" (via a remix with Lil Jon's "Step Yo Game Up"); and "We Are Number One". The latter's popularity coincided with Robbie Rotten's actor, Stefan Karl, undergoing treatment for cancer, and so fans managed to raise $100,000 for him.
In mid- to late-2016, the song "We Are Number One", a song where Robbie Rotten is teaching his underlings about villainry, quickly gained popularity after it was revealed that Robbie Rotten's actor, Stefán Karl Stefánsson was diagnosed with bile duct cancer. Remixes of the song, including "We Are Number One except everything is net" and "You Reposted in Lazy Town" ran rampant on YouTube, leading up to and following Stefán's operation. He has since performed the song with his original crew of minions in honour of the meme. Remixes are still made, often emphasizing the sound of the branch being snapped in the song.
Initially, Magnús Scheving (a multi-awarded, skillful acrobat) performed all of Sportacus' various leaps & jumps himself, but when he tore a muscle while filming in summer of 2007, Nick Jr. executives immediately stepped in and insisted on bringing professional stunt men to perform some of the character's biggest stunts, or they'd pull the plug on the show altogether. Scheving claimed it was a minor mishap that only took him a few days to recover from and wanted to keep doing his thing as normal, but as he said during an interview "they're the ones with the money", so he gave in to prevent the show from being scrapped.
(Source: Interview with Magnús Scheving on Icelandic TV news)
Shelby Young was originally cast as Stephanie. After appearing in an unaired pilot, union restrictions prevented her to play the character in the actual series.
Magnus Scheving and Stefan Karl Stefanson are the only actors in the TV show who also performed in the original LazyTown-Plays.