Find the Monkees (a.k.a. The Audition) - S1-E19
Continuity mistake: Trying to get away from the Monkees, television producer Hubbell Benson enters an elevator on the first floor. After a quick cut, Benson is shown exiting the elevator on the third floor. A potted plant and a "3rd Floor" sign were added to the scene but it is obvious the elevator is still on the first floor. A large ash tray appears in both shots and its contents are unchanged.
Answer: The Monkees TV series was very much a fantasy (this was the "groovy" psychedelic 60s, after all). Impossible things, such as items appearing out of nowhere, happened on their show without explanation all the time.
Jean G