At the 35-minute mark, Angstrom (Serling K. Brown) says, "I am large. I contain multitudes." This is a direct quote from section 51 of Walt Whitman's epic poem, "Song of Myself."
When Mark says he'll make dinner, he grabs three plates from the cabinet.
The series of red dashes and dots on the card that Red Rush's widow, Olga, gives to Debbie spells out the distress signal "S.O.S." in Morse Code.