Filming was nearly halted when Webber contracted what experts think may have been a parasite. He had spent hours lying amid the excrement and dead carcasses of road kill to get close-up shots of animals.
After a shoot, he would just "peel off his clothes and drop them right into the garbage can" before even entering his house.
Filming was so dangerous that Webber told Harrison, "If one of us dies, the other has to finish the film. The story has to be told."
But there was a different kind of danger "lurking in the background," said Webber, who lost 15 pounds and most of his will to keep working.
"I started getting these aggressive hives, almost as if I had poison oak all over my face and head," he said. "No one could stop it -- not even doctors at the university -- and no one knew what it was."
A veterinarian friend finally diagnosed his condition.
"I told him to just treat me like a dog or a cat or a horse," said Webber. "That thing nearly defeated me."
The trade in exotic animals has been escalating in the U.S., according to Harrison. For years, he got three or four calls. But in 1995, when Australian animal trainer Steve Irwin launched his popular TV show, the number of rescue calls jumped to a high of more than 100 a year in 2003 in Dayton, Ohio, alone.
"We had 19 alligators on the loose that year," said Harrison, who has appeared on National Geographic and "Inside Edition." "They were sold by the hundreds. Every kid wanted them."
The crocodiles Irwin worked with were, "the most docile animals in the world," he said. "They were overfed and can't lift their bellies off the ground."
What viewers don't see are that the seemingly tame animals on television have been surgically altered, had their claws removed and been medicated "to take the edge off."
In the real world, Harrison said, "the wild can kick our butt anytime it wants.
"You see it on TV and monkey see, monkey do," said Harrison of the reality shows that glorify exotic animals. "When you watch them raise tigers, you don't see the house torn apart when they hit the wall."
Harrison hopes the new film will result in action: State laws need to prevent sale and ownership of these animals and zoos need to do a better job of educating, he said. Television also needs to portray them in more realistic light and encourage respect for the animal and its life in the wild -- not in the backyard.
Both Harrison and Webber show enormous empathy for exotic animal owners like Brumfield, who become attached to their pets before realizing they can't handle them.
"They have an empty spot that needs to be filled," said Harrison. "It takes time to know they did wrong. Their ego and their love -- they cannot release the animal until it gets to the point when they know I am right, and they want to do the best for the lions. Terry was still their father and the leader of the pride and he feels he has failed the animals."
Said Webber of Brumfield, "What I liked about Terry was he was very honest. He didn't try to fool me or himself. He didn't paint a glamorous picture of what was going on to prevent me from doing the right thing."
Webber and Harrison developed close friendships with Brumfield that continued for months after the film was shot in 2009. They called regularly and took interest in the book Brumfield decided to write about his life with his lions. He even got a chance to view the documentary.