Given that the cactus itself is not actually visible we will have to trust the ID from the wikipedia entry where this picture is shown, but none of the other three photos are actually of Peniocereus greggii. I think this happens because the database still favors common names over latin names. There are multiple cacti that have the common name Night Blooming Cereus, but in these kind of situations with multiple plants with the same common name, people should probably not post their images without knowing the correct Latin name of the plant.
I actually have this plant though I have never caught it in flower and I have no pictures of it in my database, I will try and remedy that soon and post it.
