at one point you can [Warning Scope] (/s "see the eyes of the mask and also the nose") but I don't know. that would actually bring a lot of meaning to that scene, especially since [Warning Scope] (/s "Sarah's face was superimposed on the Jumping Man's mask in Part 15").

I think it is the white part of the roof of a house in the background.

[Warning Scope] (/s "am I the only person who sees The Jumping Man behind the column next to Carrie in the last scene???") I heard people saying it's just a roof of a house but I don't buy it, especially if you observe it really well.

[S3E18] the last scene easter egg (???)