Is the Buddha capable of making mistakes?

There is a sutta where the Buddha teaches some disciples about loathsomeness of the body. He then goes on a retreat into the forest. On his return, he finds the disciples have committed suicide as they have grasped the teachings incorrectly. The Buddha than proceeded to teach Anapana Sati as it is much safer. Does this prove that even the Buddha was capable of making mistakes? In hindsight, should he have used the ability of omniscience to anticipate the result of his instructions. Or, was this event unavoidable fruition of the disciples' past Kamma.