Gabriel references the time "before the war" when he was afraid of dying on a daily basis. This is a reference to the Great Purge that took place in 1936-1938, when up to 1.2 million Soviet citizens were executed or died in labor camps after being accused of various political crimes against the Soviet Union.
The shot of Red Square at 6:10 strategically cuts off anything to the right of the State Historical Museum. If it did, it would show the Voskresensky Gates and Kazan Cathedral, both of which were destroyed by Stalin and rebuilt in the 1990s. Neither was present in the 1980s, when the series takes place.
Chloramphenicol after which this episode is named is an antibiotic useful for the treatment of a number of bacterial infections. This includes use as an eye ointment to treat conjunctivitis. It is also used to treat meningitis, plague, cholera, and typhoid fever. It is now rarely used in the US due to the side effects.
Dylan Baker who plays a bacterial s scientist in this episode as William played a character in a series called "The Hot Zone" about a team that deals with deadly outbreaks of diseases.