When Louisa makes her wedding announcement to the arriving car full of people, her linen skirt suit changes from pale aqua in colour to beige, and back again between shots.
In a run up to the wedding, Leslie says "I made this very snazzy clipboard". The action takes place in 1935. According to the Oxford Dictionary, the word 'snazzy' has originated in the 1960s.
Apparently Louisa has forgotten that she smokes cigarettes.