The term "love-in" was one of many co-optings of Timothy Leary's famous mantra "Tune in, turn on, drop out", which gave rise to the original San Francisco "be-in" gatherings of 1967, a pun on the word "being". Another example is a "sit-in" protest, or John Lennon and Yoko Ono's public "lie-ins" from their hotel beds.
Despite its British leading man, this film was never released in the UK.
All of the exterior university scenes were shot at the "Girls School" and "Southern Mansion" sets on MGM's backlot #2. Most of the city exteriors were shot on MGMs Brownstone, Eastside, and Waterfront streets at the other end of the lot.
Except for the extras and crowd-fillers, not one of the principal actors in the film has long hair or a beard.
The park where Dr. Barnett watches the hippie celebration is MacArthur Park in Los Angeles, soon to be the subject of a hit pop song that year. It was used two years earlier for Selina and Gordon in "A Patch of Blue". Selina's tree can be seen behind Barnett and the police when they first encounter each other.