The title is a play on words from the famous line "Hell is other people" (original French: "L'enfer, c'est les autres") from Jean-Paul Sartre's 1944 play "No Exit" (French: "Huis Clos"). The line reflects a theme that appears in both No Exit and The Good Place: using people in Hell to torture each other.
Wilhelm scream when Brent falls into the sinkhole at 12:53.
Tahani remarks disparagingly, gesturing to Simone, that "some of us are under 5'10," indicating Simone is the only one with this negative trait. However, Chidi is also under 5'10" (he is 5'8"). The rest, though, are 5'10" or above.