Dennis McNally, in A Long Strange Trip: The Inside History of the Grateful Dead, sheds some more light on the evening. He writes that

admission was $17.50 at a time that $4 was rock’s absolute maximum. The situation being what it was, they naturally screwed it up royally, and it became one of their very finest professional disasters. The band and equipment arrived on time, but Bear announced that he needed a missing item back in Novato, and vanished.  While the musicians prepared themselves in a room upstairs, Bear actually went to sleep in an equipment case under the stage. When the lateness of the hour dawned on the band, they rousted him from his refuge, scourged him into setting up the stage, and at long last began to play. McIntire had induced them to echo the evening’s them and wear black and white costumes: Pigpen and Jerry were pirates, Mickey was Zorro, T.C. was an eighteenth-century bell ringer, Kreutzmann a French sailor, and McIntire himself came in a clown costume of white satin with black buttons.

So, the Dead did not exactly comport themselves in the best manner, especially considering McNally goes on to say that the boys disappeared before the mayor arrived for the ceremonies, leading the San Francisco Chronicle’s social columnist to call them the “Ungrateful Dead.”

The boys did, however, deliver some steamy music, even though it is not too difficult to find better ’69 shows. The Dark Star is particularly inspired, but the Hard to Handle, the first by the Dead, is a total mess.

Reportedly, the band opened with a Morning Dew, Alligator> Drums> Alligator, but no recording of those tunes exists. Sadly, the internet does not seem to hold any images from the evening, though there must be some floating around given the occasion.