Walter Reed takes over the role of Dennis from Charles "Buddy" Rogers.
This was Marion Martin's third appearance in the series, but as a different character than in the previous two, where she played the amorous Fifi.
Early in the film, Uncle Matt indicates he'll be going to an Air Raids Wardens meeting. This refers to actual meetings that were held in accordance with the Air Raids Precautions (ARP) organizations and guidelines in the UK, originally created in 1937. With a goal of protecting civilians during air raids, local councils were given the responsibility of designating ARP wardens and other personnel to act as messengers, emergency vehicle drivers and liaisons between police/fire departments. The ARP, which later became the Civil Defence Service (note UK spelling), lasted until the end of WWII in May of 1945.