One mistake that I see frequently is when people try to incorporate existing songs, TV shows and other movies into their own scripts. The most frequent way that people do this is by naming the songs that they want to play during particular scenes, usually over montages. While the Turtles have made more money in royalties from romantic comedy courtship montages that feature the song “Happy Together” than most groups will make in a lifetime, not every group wants their songs to be used in movies, and not every director will agree with your choice of songs. Plus, if you write a song into your movie, then the studio must pay the royalties for it, whether it fits into their marketing plan for the movie or not.
Another way that this problem comes up in screenplays is when characters are watching a certain TV show or movie. The times that I’ve seen this in screenplays have usually been when the author was trying to make an allusion to another story that is similar to his script, or sometimes to use a well-known scene to underscore a point that the author is trying to make. While this does sometimes make a scene extremely cute (such as when Elliot kisses the girl in “E.T.” while E.T. watches an identical movie scene), it’s better to leave this sort of thing out of a spec script because it will always count against you to some degree.
If you feel like you need a particular song or a TV or movie clip in order to tell your story, then chances are that you are leaning on existing works to help you tell your story instead of relying on your own creativity to make your point in a unique way. Being unique is always better, so try to take any elements of your script that incorporate copyrighted materials and turn it into something so unique and memorable that future screenwriters will be alluding to it in their scripts. Unless they’ve read this blog post, of course.