Alec Henderson (Mrs. Laura's son, killed by a German attack on France in 1915) is said several times to have been born in 1894, and this date is shown on his headstone. In fact he was born in 1888, and his headstone does not list any date.
The rain was falling down on the windshield in such a manor that was not realistic when Vivian and Bertie were searching for their English Rose. Their car and Vivian's driving were obviously done with green screen or in studio. The lighting of the car also gives away the phony look of the performance.