Bill was released from prison in 1901 and almost immediately he goes to the cinema to watch The Great Train Robbery (1903), which would be released two years later.
The intro cards state that in 1863, "the gentleman bandit" began robbing stage coaches at sixteen and committed twenty six robberies over eighteen years. Later, the card state that in 1901, he was released from prison after 33 years in San Quentin. 1901-33=1868. 1863+18=1881. (The implication is that those 33 years were consecutive and unbroken.)
After Bill reunites with his Sister they walk together toward the house to meet her husband and pass a 3 point spring tooth harrow. The three point system wasn't invented until the late 1920s.