During the Philadelphia tryout, Frankie Michaels played both Young Patrick and Patrick's son, then named Michael. This was changed when the production reached Boston.
At some point in mid- or late December 1969, Ann Miller became ill. Charlotte Fairchild took over on what was surely hoped to be a temporary basis. Fairchild had been the original standby for the role Mame Dennis. She left the standby assignment within the first year of the show's run, then she returned to it.
Although ads in the ABCs listings of newspapers continued to list Miller over the show's title through the closing day of the run, she did not return. Fairchild closed the run. It seems possible that had Miller not become ill, the show might have run at least a bit longer as the closing was not announced till Wednesday or Thursay of the final week. It seems likely that by that time, news had gotten out that Miller was out of the show, and that business was therefore notably suffering, even though she continued to be listed in the ABCs.