I found these two giants blooming in a little town called Yucca Flats in the Mojave Desert near the Marine Corps base at 29 Palms, CA. They are growing up through the sidewalk in front of a barber shop. I don't think they are saguaros, which are not native to the area anyway. They are much more massive and are blooming all the way down their branches and the saguaros we saw later in AZ only bloomed on top. These had a more feathery flower, and the saguaro has a more waxy flower. Could these be the argentinian cacti echinopsis terschecki?
They sure look like saguaros to me. The flowers in strange places could be due to being grown in non-native conditions. However, buds down the arms are within their normal behavior. I've seen a few saguaros growing naturally at the eastern edge of the Mojave. They did look a bit different then the classic Sonoran cactus.
I was staying in Joshua Tree in May and saw these, I assumed they were saguaros, surely it's the most obvious iconic columnular US cactus to plant in the middle of the sidewalk?
I can see why you might think it was E. terscheckii but those flowers are a much closer match for a Saguaro. That location is only about 100 miles from its native range, and is on the edge of the Sonoran. It may be getting some extra water which could lead it to grow and flower a bit differently.
I'm now selling plants on Ebay. Check it out! Kyle's Plants