Albert Barnes Commentary Matthew 16:5

"And the disciples came to the other side and forgot to take bread." — Matthew 16:5 (ASV)

And when his disciples were come to the other side. That is, to the other side of the Sea of Galilee. Mark says that he entered into a ship again, and departed to the other side. The conversation with the Pharisees and Sadducees had been on the east of the Sea of Galilee. They crossed from that side again to the west.

Had forgotten to take bread. That is, had forgotten to bring a sufficient supply. They had, it seems, not more than one loaf (Mark 8:14).