Character's first names vary throughout the series: Mr. Lucas is variously James or Dick; Mr. Harman starts as Harry, then becomes Beverley; the cleaner has three different names, always played by the same actress.
Throughout the series, the scripts constantly change the location of the Ladies' and Gentlemens' departments, sometimes referring to it being on the third floor, sometimes on the fourth. Also, the theme song lyrics indicate the department is on the first floor.
The sex of Mrs. Slocombe's cat, Tiddles, frequently changes from him to her.
Telephones change locations and types, either wall mounted phones on the ends of the display cases, at other times desk models on top of the counters. Additionally, cash registers come and go.
Mr Humphries continually goes from either living with his mother to living on his own with his mother always coming to stay.
Throughout the series, the entire staff of the floor takes breaks together. That would mean that the entire floor would be closed due to lack of employees during break times. Indeed, one episode specifically deals with this problem. Mr. Grace feels that they are losing too much business during this hour, and pushes the lunch break back to later in the afternoon, leading the staff to hit the roof.
Often during the opening credits, women dressed identically to Miss Braums and Mrs. Slocum are seen in the background working around displays or behind counters- obviously part of the sales staff, but they are never included in anything the other characters do.