The plot revolving around a fire on board the Soyuz T-13 and possibly returning with only Savinykh on board was added for the movie, in reality the crew took great care in ensuring all water had evaporated before turning on any electrical systems.
Easter egg: At 1:03:16 after cosmonauts have measured their body temperatures and stowed thermometers into medical cabinet, a book by Viktor Savinykh "Salyut-7, diaries from the dead station" released in 2017 is seen tucked behind the medicine cabinet.
On February 7th 1991 the Salyut 7 fell down in Argentina.
Shubin refers to three cosmonauts who died in space. This happened during the last minutes of the Soyuz 11 mission in June of 1971. The capsule was designed to separate from the rest of the spacecraft via a set of small explosive bolts that were supposed to fire in sequence. It is theorized that they accidentally all fired at once, with the impact causing a valve to open. At the time, the space program was eschewing space suits for descents and the crew died painfully in a vacuum, having only some ten to fifteen seconds to react while enduring extremely disorienting pain. As stated in the movie, nothing could have been done to save them.