We've all heard of movies where the cast and crew dealt with tough, grim subject matter by keeping the atmosphere on the set light and playful, or by blowing off steam at the end of the day.
"I don’t think I went out to dinner once while I was making this movie," Eckhart told theWrap's Sharon Waxman during a Q&A that followed theWrap Screening Series presentation of "Rabbit Hole" at the Arclight Sherman Oaks on Monday.
"My kid is dead. Why do I want to give that up? I went to keep that close to me. I want to go to bed, get up in the morning and go right back to that place.
"If I go to the store and see a woman pushing a baby carriage, that's not just a woman with a baby. You think, oh my God, that's the baby I don't have. Everything becomes a point of entry into the film."
Actress Sandra Oh, who plays a woman who's been in a counseling group for parents who've lost children, agreed that the atmosphere was charged and serious – following the tone set by Kidman, who starred in the film and also served as one of its producers.
"The subject matter is difficult," said Oh. "You have to be there for 14 hours, and Nicole does it in a very controlled way. There was lots of quiet."
Added Eckhart, "Nicole didn't make too many jokes on this movie. I tried to get in her face and make jokes sometimes."
To research his role as a father trying to cope with debilitating grief, Eckhart says he went to grief counseling, scoured the Internet ("the best tool ever for actors") for video diaries, and remembered a friend of his who'd accidentally run over his young son.
"I don't want to say that it ruined his life, but it drove him inside, into the dark," said Eckhart. "He got a divorce, he struggled with alcoholism, he went through the guilt and the self-hatred and all that stuff."
"Rabbit Hole" began as a Pulitzer Prize-winning Broadway play by David Lindsay-Abaire, who was inspired to write it following the birth of his first child, when he remembered a Julliard writing teacher's challenge to write about what scares you the most.
Mitchell, the director of "Hedwig and the Angry Inch" and "Shortbus," had dealt with a premature death in his own family: "His brother died when he was four years old," said Eckhart, "so he had a personal relationship with loss and grief."
Eckhart himself became involved fairly late in the process, when Kidman called him and asked if he was interested. The actor was in Puerto Rico shooting "The Rum Diaries" with Johnny Depp at the time, and was intrigued by the prospect.
"I thought, Nicole is producing this, and she's starring in it, and it's a Pulitzer Prize-winning play," he said. "If ever Nicole is gonna go for it, it's gonna be in this movie. And I want to be along for the ride."
The film had a small budget – Eckhart said $5 million, but Oh insisted it was much smaller than that – and little time for Kidman and Eckhart to rehearse the interplay between a married couple who, the actor said, "can no longer relate to each other mentally, physically, spiritually."
The two actors, he said, didn’t always see eye-to-eye – but that helped as they portrayed a couple who are working through the grieving process at different speeds.
"The consensus is that you never get over it, and you just assimilate it into your life," said Eckhart.
The toughest part of the film, he added, was not reaching that place of grief, but making it his own.
"As an actor, you have triggers for the things you do – crying, all of that," he said. "The problem is, can you make it as personal as you possibly can?"
When he fails to do that, he said, it hurts him badly.
"Today, I am as hungry to do good work as I ever was in my life," he said. "I ache to do good work, and I hate not doing good work. A film that doesn’t work takes me 10 years to get over. It burns me every single day."
Both actors were full of praise for Kidman – who, said Oh, "connected to this in a very, very deep emotional way. It's about what we fear the most, our most hidden and private places … And she's a truly magnificent actress, and a serious artist."
As a producer, though, Kidman was hardly extravagant. For much of the shoot, Eckhart said, the filmmakers and actors lived in the house that was also used for shooting.
"Nicole had one bedroom," he said, "I had another, and we shared a bathroom."
But the actor said he was intimidated sharing that bathroom with his leading lady and producer ("what if I'm in the bathroom and Nicole wants to use it?"), so he switched and shared one with the crew instead. John Cameron Mitchell, meanwhile, slept in the little boy's bedroom, and used the Kidman/Eckhart bathroom to take baths.