As a promotional stunt, Lionsgate gave away/delivered free marijuana at the San Diego Comic Con to anyone with a medical marijuana card.
The movie's title and plot are a reference to the CIA's secret research project called "MK Ultra".
Although many people have heard of MK Ultra, it's often misunderstood. In reality it was a project to combine what the American government knew about mind control with what the Germans knew about this subject.
The letters MK use the English word for "mind" and the German word for "control". MK = Mind Kontrolle. "Ultra" refers to the highest level of security classification.
Its main purpose was to come up with ways to induce their subjects with MPD (Multiple Personality Disorder), and find out how these alter personalities could then be triggered on command (sometimes by simply uttering an innocuous phrase) to be utilized for other means which the subject generally would have no recollection of afterwards.
The project began in 1953 after the American government had brought scientists from Nazi Germany to America under Operation Paperclip, and officially ended in 1973. Since then the project has continued under the name Monarch mind control.
In the film Le Bon Gars (2015), another film written by Max Landis featuring an agent from the Ultra Program, there is a wedding reception for a couple named Mike and Phoebe.
Uma Thurman was cast but her deal never materialized and Sharon Stone replaced her. When "scheduling issues" caused Stone to drop out, Connie Britton stepped into the part.
Author Stephen King said via Twitter that he loved "American Ultra" and called it, "fresh and exciting. Very cool."