Hill's 1968 selection of Halloween costumes is interesting, a real mixture of old and new.
|1967 Mr. Spock Costume|
(currently on Ebay)
Instead of demonstrating the Vulcan salute ("Live long and prosper") however, the kid dressed as Mr. Spock is doing the Vulcan Gleeful Wave.
Small wonder that the kid wearing the Dr. Dolittle costume is shown bringing up the rear. The movie was an infamous bomb (I oughta know, we saw it at the theater.) He'd be better off converting his Dr. Dolittle costume into that of a classic top-hatted hobo.
If you're wondering what the other costume in the ad is supposed to be, it's a witch – and here it is in color (below), courtesy of the Blood Curdling Blog of Monster Masks.