According to Jon Hamm, the production's pursuit of historical accuracy is such that series researchers will insist on knowing weather conditions, news items, and popular culture for a particular period related to the script's time frame.
The actors do not smoke real cigarettes. They smoke Ecstacy herbal cigarettes, which are tobacco and nicotine free. Show creator Matthew Weiner said in a New York Times article, "You don't want actors smoking real cigarettes. They get agitated and nervous. I've been on sets where people throw up, they've smoked so much." When asked what it's like to smoke herbal cigarettes, Jon Hamm (who plays Don Draper) told Vulture, "Terrible. They taste like a mixture between pot and soap."
There is no improvisation on set. The scripts are followed verbatim, and any possible change is discussed with Matthew Weiner first.
The series spans ten years; the pilot takes place around March of 1960. The series finale occurs in October 1970.
Nearly a year elapsed between the filming of the pilot, Smoke Gets in Your Eyes (2007) and the second episode, Ladies Room (2007).