Character mistake: Colonel Breen theorises to Quatermass that the spaceship is an experimental German V-weapon from the second world war: However according to the story, the underground station (Hobbs End) was dug in 1927: The V-weapons first landed in London in 1944, so how was it possible for a V-weapon to land where it did underground, impacted soild in clay right next to a deep level underground railway station seventeen years later without anyone noticing at the time? Breen should realise that his theory makes no sense.
Character mistake: While one of the Soviet mission controllers does speak with a native-sounding level of Russian, the other controllers and the cosmonauts sound obnoxious at times; strange anglicisms or outright English words are sprinkled into the script, such as the word "pressure" in the middle of an otherwise Russian sentence, not to mention the many grammatical errors.