The horse Murzilka is named after the title character of 'Murzilka', the most popular children's magazine of the USSR. The magazine, launched in 1924, is still published today and has been included in Guinness World Records as the longest running children's magazine.
Tatyana Lyutaeva played the mother of Aleksey (Aleksey Chadov). In real life, she is the mother of Agnia Ditkovskyte, who played Nastya.
The four main characters of the film have the same first names as the actors who play them, but their surnames that Aleksey sees briefly in a school photo album are different: Aleksey Chadov is Aleksey Nakhimov in the film, Artur Smolyaninov is Artur Donskov, Konstantin Kryukov is Konstantin Rudovsky, and even Timur Yunusov, who plays himself, is called Timur Vinogradov while Timati's real surname is Yunusov.
Out of 27 soundtracks mentioned in the credits of the film, the names of four contain the word "zhara" (heat) and the names of another three contain the word "Moskva" (Moscow). The film is called "Zhara" ("The Heat") and is about a hot day in Moscow.