Despite claims made by your stoner buddies most actors aren't actually smoking pot in movies like Pineapple Express, and most actors haven't even smoked real cigarettes on set since the late 90s.
The truth is- look-alike substances have always been used by filmmakers if for no other reason than drugs are illegal and drug use on the set could result in some serious fines or worse.
And while pot laws have loosened up quite a bit over the last few years actors would still have a hard time remembering their lines if they were really getting stoned while filming. (Video is NSFW)
So according to veteran prop master James Butcher the actors are smoking legal "buds" that promise to offer a "multidimensional smoking experience unlike you've ever tried before"
In an effort to make sure these "buds" worked as an on-screen replacement for marijuana James "smoked an enormous amount of it" and "didn't really feel anything".
But what about the cigarettes? They're really smoking herbal cigarettes, which look right but supposedly aren't as harmful as cigarettes because they don't contain tobacco or nicotine.
Now if that isn't an ill informed statement, I don't know what is.