20 Things You Didn't Know About Star Trek IV: The Voyage Home
2. You've Blocked My Car, I'm Getting A Part
Layla Sarakalo plays the part of the young woman from whom Uhura and Chekov ask directions. She runs her hand through her hair, unable to answer them, and advises them that the Naval Base in Alameda is most probably across the bay - in Alameda.
This scene is a funny placeholder that was effectively left in for the hell of it. Sarakalo was not an actor. She had returned to her car to discover that it was blocked in by the filming crew and therefore she couldn't leave. Rather than create a fuss, she asked if she could have a walk-on role in the film.
For the scene in question, Walter Koenig and Nichelle Nichols attempted to stop random passers-by on the street with their questions. They were observed by a cop - a hired actor - but none of the non-speaking roles had been professionally cast. Crucial there is the term non-speaking, as these were simply extras. Sarakalo's inclusion of lines actually caused a tiny headache for the crew, who then had to chase after her - and induct her into the Actor's Guild - so that her lines could remain.
All agreed that the comedy was worth it and the scene was left in the film.