The skydiving plane is a Lockheed Model 12A Electra Junior, FAA# N1161V (now N12EJ), built 1936. Once owned by Art Scholl up to his death, N12EJ is a true veteran, used by the British for photo reconnaissance from the start of WWII (and months prior with concealed cameras); it was installed with the first "teardrop" observation window and sported the first "sky camouflage" ("Camotint") paint job. Field Marshal Albert Kesselring was once allowed the controls during a pre-war "joy ride" over Germany; Hermann Göring was certainly aware of the plane. In September 1940 it was badly damaged in its hangar by a German bombing raid and it was shipped back to Lockheed (Burbank). It has appeared in other film and TV projects.
Happy hour refers to a time in the mid-afternoon that some bars offer drinks or snacks at a discounted price. It is a way of driving business during a typically slow time of day. The reason why happy hours is banned in some places is because it reduces the number of drunk driving accidents during the busy and more accident-prone afternoon rush hour. Massachusetts was one of the first U.S. states to implement a statewide ban on happy hours in 1984. Cheers previously had a happy hour, referenced in the third episode of season one, before the ban took effect.