"Given he has such a lack of respect for the first amendment and his wife is such an animal-rights activist – it is shocking he thought he could show his face here.
"The funny thing is most people didn't recognise him or care."
He's now facing public criticism from animal rights group Peta, which called his attendance "extremely disappointing" due to rodeos' reputation for enabling animal "suffering".
"It's extremely disappointing to see that Prince Harry made the misjudgment to attend a rodeo, a crude, old amusement for bored cowboys who view animals as nothing more than things," Peta assistant manager Catie Cryar said in a statement.
"In these events, participants use electric prods, flank straps, and spurs to burn, wound, terrorise, and provoke animals who are trying to flee for their lives."
Cryer added: "Animals commonly sustain broken bones, punctured lungs, snapped necks, or torn muscles, and they sometimes die in an arena — and even those who don't end up scared out of their wits at a slaughterhouse — so anyone who cares about animals should avoid these spectacles of suffering."
Several other animal rights groups have spoken out against rodeos in the past due to their treatment of horses, who are forced to perform and can often suffer fatal injuries.
Meghan Markle is said to be a staunch animal rights activist and has reportedly even talked Harry out of attending royal fox hunts.
Mayhew's media officer Satah Hastelow previously called Meghan a "champion of animals and animal welfare".
Rodeos have been traditional entertainment in states like Oklahoma, California, Colorado, Texas and Wyoming for years, with organisers insisting their animals are well looked after.
But animal rights campaigners have branded rodeos "a cruel form of entertainment that involves the painful, stressful and potentially harmful treatment of livestock".