When the pre-Broadway tryout opened in New Haven and then in Washington, DC, David Burns played both Prologus and Senex.
It may be that Zero Mostel took over as Prologus and sang "Love Is in the Air" while the show was in Washington, D.C. but we're not certain of this. We know that by the first Broadway preview, Zero Mostel was Prologus as well as Pseudolus. By that time, "Comedy Tonight" was in the show and "Love Is in the Air" was gone (except for underscoring at the top of Act Two).
The production announced a closing date of August 8, 1964, but according to an article in the New York Times on Friday, August 7, an upturn in business caused the run to be extended three more weeks.
An Actors Fund benefit performance was given on Sunday evening, Sept. 23, 1962.
The production was originally scheduled to open on Broadway on May 3, 1962. Broadway previews were to have started on May 1. The opening was postponed to May 8 because of the new material that had been added to the show. Previews started, as originally scheduled, on May 1. The number of previews was thereby upped from three to eight. Performances that were to have been post-opening instead became previews.
Jerome Robbins was originally to have directed the show, but he ended up deciding not to direct. George Abbott instead directed, but when the show ran into serious problems during the pre-Broadway tryout, Robbins came in to help out. He suggested that a new opening number be written and he staged that new number ("Comedy Tonight"). He also made many adjustments and additions to the staging. Many of them were small changes, but they added up to a good many changes.
After the opening, Robbins sent to the show's producer, Harold Prince, an extremely detailed list of his contributions, along with a demand for more in royalties than must have been originally offered to him. The letter can be found at the Library for the Performing Arts in New York. It was on display at the library in an exhibition titled "New York Story: Jerome Robbins and His World" in 2008.
At least two books — Greg Lawrence's Dance With Demons: The Life of Jerome Robbins and Amanda Vaill's Somewhere: The Life of Jerome Robbins — state that Richard Coe's Washington Post review of the tryout was headlined: "MR. ABBOTT, CLOSE IT!" This is not true. Coe reviewed the production twice during the tryout. He reviewed opening night, and then came back later to see it again and re-review it. Neither review had that headline. In fact, in neither review did he even make the suggestion that the production should be closed.