The Red Light, Green Light doll was borrowed from a Korean adventure park and had to be returned after filming ended. While it has been returned to where it belongs, it is now missing its right hand.
The workers that run Squid Game are in a hierarchical structure. Status is based on their mask symbol. Circles are low-level workers/drones. Triangles are a mid-level armed security force. Squares are supervisors who manage the workers and day-to-day operations. Front Man is the supervisor for the games and the entire island. Unlike the others, he wears all black and a uniquely identifiable mask.
The sequence where the players walk up and down the stairs is reminiscent of "Giallobus" by M.C. Escher.
Hwang Dong-hyuk conceived the idea for the series based on his own struggles with money and what he saw as an increasing class disparity in his native South Korea.
Netflix originally wanted to title the series "Round Six" as they felt that Squid Game (2021) would have no resonance outside of South Korea.