The events in this episode take place in Summer 1906 (before those in the previous episode), according to a caption in the opening titles.
In the 40th anniversary DVD release episodes 6 and 7 are reversed.
This episode takes place during the summer of 1906.
Although appropriate for the time period, the green wallpaper seen in the restaurant was likely toxic. Despite its vivid and eye-catching nature, doctors eventually discovered that green wallpaper could kill. The ink contained arsenic and often flaked off the paper only to be inhaled by those nearby, while moisture, abrasion, or heat caused the release of toxic vapors.
The title is a reference to John Keats' Ode to a Nightingale.