The Easter Egg items below may give away important plot points.
Several episodes hides the address and logo of Mikael's real life Portfolio Msun.se. The address is visible on his T-shirt in episode 3, as well as on a hoodie sleeve in episode 5.
In episode 5, Melody is watching Melmic episode 4, and Mikael is scrolling through Melmic's Facebook Page.
An Easter Egg may or may not be found on this site.