Sam's sound effect remote used on the show is the only one in existence. They have used the same remote since the pilot. Dan Schneider kept it in his home when it was not being used for filming to make sure the remote wasn't lost.
Each of the four main cast members - Miranda Cosgrove, Jennette McCurdy, Jerry Trainor and Nathan Kress - all made their Nickelodeon debuts on a previous show of Dan Schneider's. Miranda was a main cast member of Drake & Josh, and Jerry was a recurring cast member on that show. Jenette was in an episode of Zoey 101, and Nathan made his first appearance in an episode of Drake and Josh.
In one of the final episodes of Drake & Josh (2004), a movie title listed on the reader board of the Premiere was "Now She's Carly." This was a reference to Miranda Cosgrove (Megan on Drake and Josh) moving on to play Carly on iCarly.
The original title of the show was "Starstruck" and the plot followed Carly, a regular girl, who is cast on her favorite TV show. The idea was then changed to her getting her own show, and then changed again to her creating a web show.
Freddie often speaks some of his lines in Spanish. Series creator Dan Schneider has often stated on his blog that the reason behind Freddie's random Spanish outbursts will be revealed in a future episode, but it never was. In the final episode, Freddie began to explain it but was interrupted.
Spencer's friend "Socko" has been mentioned numerous times throughout the shows run, and it became a gag in the writing room to mention Socko's friends and family members along with their professions. Socko makes Socks, his brother Tyler sells ties. Rob is a thief. Taylor is a tailor. Otto is a car salesman. Hattie is a hat maker, cousin Isaac is an optometrist, etc.
Most of the furniture in Carlys apartment was made by "Jellio," a company who makes furniture in the shape of cupcakes, ice cream, Rubiks Cubes and other random objects. To name a few, the hanging monkeys on the large window, the lamps, and the various colored gummy bear lamps were all designed for the show. Recently the Gummy Bear lamps have become available at the Jellio website.
Most of the comedic lines are improvised on set by the writers, or Dan Schneider. Most of the time the script has very few comedic lines and the comedy in the final cut of the show was improvised. The actors aren't allowed to improvise anything unless they ask the director or Mr. Schneider.
Lots of times, the show will reference Drake & Josh (2004), another show that Dan Schneider made. This includes Carly mentioning a Peruvian Puff Pepper, although a pepper of the same name was mentioned in Drake and Josh. Another reference is Grandad mentioning the Parker/Nichols hotel. Parker and Nichols are the last names of Drake and Josh in the series.
In a few episodes, Carly makes "special lemonade" that nobody likes to drink. This was written into the show because on Drake & Josh (2004), another Dan Schneider show, Josh Peck's character would make Limeaide that nobody liked to drink.
Season three episode "iWon't Cancel the Show" is the only episode Jennette McCurdy was absent in. Her excuse for being absent was for being hospitalized due to a high fever. The original script of that episode consisted of Freddie visiting Sam in jail, giving her an appearance. With such a meager amount of time for discovering her illness, the writers erased that scene and improvised for something else to include.
Recently, Carly, Sam, Freddie, and Spencer wear several custom made t-shirts that reference several jokes from the show such as Sam wearing one that says "Church Pants," a joke from when Freddie says, "she flipped out when I spilled one drop of mustard on my church pants!" in a past episode.
iCarly is the "first scripted series that will incorporate kid-created original content," according to Nickelodeon's marketing campaign and press kit. However, the content usually feature actors instead of real people.
Socko makes socks, his brother Tyler makes ties, his cousin Rob is a thief, his sister Taylor is a tailor, his cousin Otto sells cars, his sister Hattie makes hats, his cousin Isaac is an eye doctor, and his cousin Boomer sells explosives.
In the opening credits sequence before the music starts, some of the links in the favorites section on the screen include "TheSlap," the blog from Dan Schneider's show Victorious, and "Danwarp," the name of Dan Schneider's actual blog.
In Zoey 101, which is another show produced by Dan Schneider, when Chase is shooting baskets, he said if he had a zebra he'd name it Zebo, which is the name of the dinosaur in the iCarly episode "iCarly Saves TV."
The reason why "Pear phones" are a thing in iCarly, Zoey 101, Sam & Cat, and Victorious is because Nickelodeon didn't want to pay to use Apple's logo. This technique is also used when they talk about Inside Out Burger, which in real life is In 'n Out Burger.
With the exception of the clip episode, which is the only episode Freddie doesn't appear in, Miranda Cosgrove (Carly), Nathan Kress (Freddie) and Jerry Trainor (Spencer) are the only 3 to appear all of the episodes. Jennette McCurdy (Sam) missed 2 episodes and one of which is the clip episode.
In the episode where Spencer is at the children's arcade, Gibby's younger brother, Guppy, is reading a book called "Nifty Shades of Beige." While reading, he makes a face as if he just read a very intense part of the book. "Nifty Shades of Beige" is a parody of "Fifty Shades of Gray."
In the episode, "I Beat The Heat", Sabrina, the girl who was video chatting Freddie frequently, looked really tall many scenes. When Freddie offers her a seat, and when she takes the seat, you can clearly see her shoes, which have no heel, making her seem really tall. But a few scenes later, like when she crushs Carly's project, you can see she is wearing at least four inch heels; so she isn't as tall as they make her seem.