This film depicts the birth of Man's son Ip Ching as happening in the 1950's. Ip Ching was actually born in 1936 and was a teen living with his brother in Mainland China at the time this movie is set.
Ip Chun elected to stay in Mainland China and would not join the family in Hong Kong till 1962.
In the final fight, the announcer's microphone appears to be a modern condenser microphone. The film takes place in the 1950's.
(around 41min) on the fight with master Chang the Ip man double appears when Chang turn's around, that moment the camera faces the Ip man but it isn't him .