Not a Hidden Easter but rather a secret Award lara... The Three Gunslingers with the White Hat are part of the Three Amigo Award it's an Unknown Award. Once you hire all three the hat turns black and they gain a mask. They are the 130 cost Slinger so just keep building and destroying don't bother to hire until you get 1. Hire destroy repeat.

The other three unknown Awardsbeing. Beehive Bear.

Treasure Hunter (must complete Cow Skull Quest and a 2nd Treasure Quest in Gunslinger Gultch.)

Sheep Farmer (also done in Gunslinger Gultch the Wild Horse lasso with a citizen and take to well. Unlocks quest complete Quest now you can raise Sheep)