Marcelle Larice wore a prosthetic butt in all her costumes to make her booty look bigger than it actually was. This is why Yo never wears a bikini like the rest of the models.
Sung Hi Lee and Maria Arcé previously starred together in Girl Next Door (2004).
During Yo's photo shoot, Gerd tells her to make her booty "like the Hindenburg." One of the hypothesized causes of the Hindenburg's explosion was a gas leak, which is exactly what happens to Yo's butt.