Based on Dan Aykroyd's personal experiences. In 1978 he was pulled over for speeding in a rural town in the Northeastern United States. The police officer took him to the local Justice of the Peace in the middle of the night for a trial.
Dan Aykroyd later agreed to play the giant adult baby Bobo as well, after no one else wanted to play the part, and found it stressful to play two parts in heavy makeup while simultaneously directing and producing.
Chevy Chase did not like the script, but took the leading role because he wanted to work with his friend Dan Aykroyd and thought they could improve the movie by improvising. Chase later said that Aykroyd took a huge career hit when the movie bombed because he had taken on so many roles (director, writer, actor, and producer) that no one else had a high enough profile to take blame for how bad things turned out.
The crew enjoyed working with John Candy and Demi Moore, but Chevy Chase (as he is infamous for) proved to be a nightmare. Chase was verbally abusive to everyone on set, tried to speak on Moore's behalf about her "skimpy" costume, and stated that he had more worth than Aykroyd because Chase had the bigger paycheck. The crew was furious at Chase's treatment of Aykroyd, with one crew member even threatening to drop a brick on Chase's head if he ever spoke to the director like that again.
Bertila Damas and Taylor Negron spent a lot of time with one another, during pre-production, rehearsing and building their characters together as they portrayed brother and sister in the film. In fact they actually wrote much of their own dialogue with Dan Aykroyd 's approval.