Carly's birthday changes from January 14th to July 24th.
Throughout the series. Carly and Spencer's dad is mentioned being in the Navy but when he makes his physical appearance in the finale, he's wearing an Air Force uniform.
Throughout most of the early seasons. iCarly fans claim they don't know who Spencer is. However this may be due to Spencer barely participating in the show.
In some episodes the iCarly-crew is broadcasting the web show live from places without any internet connection, where it would be impossible to broadcast a web show with the equipment, that is showed in the series, like a supply cabinet in school or an old castle. They need an broadband internet connection for video and audio. And a wireless connection would not take that much signals and send it in real-time.