Mary takes several huffs from a joint with the tip distinctively glowing but never exhales smoke.
When Ben's mother receives call from Mary's mother, the guy she was with walked by when the cellphone ringing but, it was not answered, going to voicemail. However, he hears the voicemail. Cellphones don't automatically turn on audio when someone is leaving a call. So, he shouldn't of known where they were to inform Terrence and the others.