According to his "tombstone", Bret Maverick was born on April 7, 1847. April 7, 1928 was James Garner's birthday.
Bret's "tombstone" says his death date is Sep. 21, 1876, the date in this episode setting. Bret is then 29, with his tombstone birth date of Apr. 7, 1847.
The lyrics of the Maverick theme song are sung over the end credits for the first time in the series' run.