The songs Scarlet Ribbons (For Her Hair) (1949), and Danny Boy (1910), sung in this episode, weren't even written yet in the time period (late 1860's/early 1870's) in which this episode is set.
The song "The Old Rugged Cross" performed in this episode was also composed much later, in 1912, with lyrics and music by George Bennard. It was not published until 1915.
The piano player Mike is Wayne Newtons' real life brother.
Adam (Pernell Roberts) is mentioned by Little Joe as being in Paris.
Scarlet Ribbons was not written until 1959 and would not have been sung in the time of this Bonanza episode.