In the original e-book , it had another ending scene than the one that was published.

Watney finished his two slices of pizza and a coke. He had another half-hour to kill before going back to Johnson Space Center. Leaving the pizzeria, he sat on a public bench just outside.

Next week would be busy. He would be meeting the Ares-6 Engineer. He had read her file, but had never met her in person. He wouldn't get much time to relax after that. The following six weeks would be filled with constant training as he tried to impart as much knowledge as he could.

But that was something to worry about later. Right now, he took a deep breath of the fresh air and watched the people go by.

“Hey, I know you!” came a voice from behind.

A young boy had strayed from his mother. “You're Mark Watney!”

“Sweetie,” the boy's mom said, embarrassed. “Don't bother people like that.”

“It's okay,” Watney shrugged.

“You went to Mars!” the boy said, his eyes wide with awe.

“Sure did,” Watney said. “Almost didn't make it back.”

“I know!” said the boy. “That was awesome!”

“Sweetie!” The mom scolded. “That's rude.”

“So Mr. Watney,” the boy said, “If you could go to Mars again, like, if there was another mission, and they wanted you to go, would you go?”

Watney scowled at him. “You out of your fucking mind?”

“Okay time to go,” the mom said, quickly herding the boy away. They receded into the crowded sidewalk.

Watney snorted in their direction. Then he closed his eyes and felt the sun on his face. It was a nice, boring afternoon.