Easter Eggs and Hidden Details in RDR1.

The Repentance Rock Mystery Site

Middle of the small circle under the R of Repentance Roc and left of the Rio Bravo is a weird ceremony site with some mysteries symbols around it.

Interracial Couple in The Old Bacchus Place

There is a black man and a sick white woman living together in a cabin in The Old Bacchus under the Thieves' Landing. It's a nice little detail from Rockstars showing how shunned interracial couples were at the time the game is set.