[6][b] The two Kims in the film communicate with English since the director wanted to reflect that they are different from the mainstream society that they are part of which use Korean and the isolates would have their own symbols rather than language.

[7] Actress Jung Ryeo-won said the favorite parts of the scenario were her character's scar on her forehead since she thought she would never do such makeup ever again on her career and the theme of hope.

[8] Actor Jung Jae-young had to lose 7 kg for three months and did not trim his fingernails and toe nails and cut his hair to portray the look of a person who drifted to an uninhabited island.

As he learns to survive on the island, his cry for help scrawled in the sand is seen by Kim Jung-yeon (Jung Ryeo-won), a hikikomori who spots him while engaging in her nightly habit of photographing the moon.

After overcoming her anxiety and desperately running across the bridge to find Seong-geun, Jung-yeon manages to catch up to his bus after the civil defense drill stalls it.