With An American Werewolf in London I was really concerned. I was 18 when I wrote that script and when we began working on the project that was still the basic script we worked from. When we looked into it we found that the cartoon cinema at Picadilly was no more. They had turned it into a porno theater and as a result I decided to update the script and make it contemporary. People like Aykroyd, Eddie Murphy, Steve Martin are all known for their abilities to improvise.
Every actor is different.
On the other hand you can take that as a compliment, because obviously my work paid off. If you decide to improvise during the shoot, you only do it within certain parameters. I truly enjoyed the movie, but I know many fans were disappointed. Blues Brothers 2000 was a movie that Dan and I wanted to make. There was a lot of Rhythm and Blues around at the time that we really wanted to put on film to commemorate it.