Not a goof
The goof section says it was a goof for Captain Parmenter, "The scourge of Appomattox" to be awarded the Silver Star in 1865.
The first episode show show he was awarded the Medal of Honor, not the Silver Star, and was cut by the pin, and so was given the Purple heart, "the only person ever given a medal for getting a medal". The Purple Heart was not awarded at the time and is an anachronism.
The person who wrote that goof might have forgotten or never seen the first episode, but doesn't the theme song played in every episode of the first season say:
"His Medal of Honor pleased and thrilled
his proud little family group
while pinning it on some blood was spilled
and so it was planned he command -- F Troop!"
03/02/15
Here is a link to an photo from the 1860s s of how the Medal of Honor was worn at the time - it is the star shaped object right above where the two belts cross.
http://www.bing.com/images/search?q=willie+johnston+medal+of+honor& ;amp ;qpvt=Willie+Johnston+Medal+of+HOnor&qpvt=Willie+Johnston+Medal+of +HOnor&FORM=IGRE#view=detail&id=A062A16AFF5C7F9C3695799451A6F4 EB313ABDE8&selectedIndex=1