When Kenneth Griffith climbs into the attic and uses the wireless, his Morse code is accurate. He sends out an SOS and calls "all large power stations."
When first seen, the music society are listening to a recital by "Georg Brunch", according to a poster, though it's misspelled as "Geog".
The radio equipment Jimmy Ellis used to warn the authorities about the attacks consisted of a transmitter T1154 and receiver R1155. These were used in Royal Air Force bomber aircraft during WW2, and were still in use in some Royal Air Force Air-Sea Rescue boats into the 1970s.
Final film of Helen Harvey.
Despite looking much older, Liam Redmond (Commander Brennan) was actually only 38 years old when this film was made.