Based on a pilot of the same name produced by and for Cartoon Network and released online in 2016. The short featured two characters who were later scrapped entirely for the series: Shane, a friend of Reggie, and Tristan, a school bully.
Similar to Neverland in Sir J.M. Barrie's Peter Pan long periods of time spent on Endless makes you forget about life on Earth and you soon lose track of time.
In the original short Endless and all of its inhabitants were a creation of Reggie's own imagination, in the series Endless is a place that has existed long before she had been born.
Kelsy Abbott, Steve Agee and Matt Berry are the only cast members from the 2015 pilot episode.
Reggie's red hair could be an homage to Disney's adapted version of J.M. Barrie's character Peter Pan who, like Reggie, does not want to grow old and has adventures on a magical island.