At around 45 minutes Jill develops a photograph of the fake doctor. However, the picture is is standard portfolio shot of Peter Arne with a plain background. When she took the photo he was sitting in an armchair with other furniture behind him and had surgical dressings on his face.
Rainer's heartbeat stopped for very much longer than 7.5 seconds.
Radioactive conversion of elements was already well-known at that time, e.g. Berkelium was synthesised by Seaborg in 1949.