The What's Up on What's Up Doc?

After seeing The Last Picture Show, Barbra Streisand wanted to work with director Peter Bogdanovich.

“It was the fastest I've ever had a movie come together,” Bogdanovich remembered.

He decided that a screwball comedy would be perfect for the new project.

“She's so good as a comedienne that it was easy for her. That's why she didn't want to do comedy that much – it was too easy for her.”

What’s Up Doc? became Bogdanovich’s highest grossing movies, and it broke the 30-year house record at Radio City Music Hall.

1. A big star was a big inspiration.

What’s Up Doc? drew heavily from Bringing Up Baby, including the tuxedo-tear gag (read about that film here). Bogdanovich was a fan of the classic screwball comedy and its leading man. "[M]uch of my direction was in pointing out to Ryan various takes of line-readings that essentially mimicked or recalled [Cary] Grant,” He remembered. "As Hawks had always said, 'When you steal, steal from the best." Cary Grant even gave Ryan the following advice: "wear silk underpants while shooting the film".

2. It was Kahn’s film debut.

However, at first, Madeline Kahn was worried about taking the part, fearing it would hurt her budding Broadway career. “Well, I thought that was a pretty tasteless title... But then I read the script, and I knew it would be good, and working with Ryan and Barbra couldn't hurt,” she said. Despite being her first film, she received third billing. O’Neal remembered, “She was naturally funny. It was her instinct. She could make you belly laugh." Kahn would later work with Bogdanovich and O’Neal in Paper Moon.

3. A plane ride inspired singing.

Bogdanovich was on a plane when he heard a recording of Ethel Merman singing Cole Porter’s “You’re the Top”. He said, “I just thought it would be a good opening number, and it would be fun to have Barbra sing it.” The film includes two songs by Streisand – “You’re the Top" and "As Time Goes By". It also includes a performance by Bogdanovich himself. He can be heard singing "Santa Lucia" when Streisand is outside of the pizzeria.

4. There are two O’Neal connections.

At the end of the film, Barbra Streisand’s character says, “Love means never having to say you’re sorry.” That line is from her co-star Ryan O’Neal’s big hit, Love Story. The film made O’Neal a star, and he was nominated for an Oscar for his performance. O’Neal’s mother, Patricia, also has a cameo on the airplane.