 One of the most difficult effects in the film was Jessica's dress in the nightclub scene, because it had flashing sequins, an effect accomplished by filtering light through a plastic bag scratched with steel wool.Regular Zemeckis collaborator Alan Silvestri composed the film score, performed by the London Symphony Orchestra (LSO) under the direction of Silvestri.Zemeckis joked that "the British [musicians] could not keep up with Silvestri's jazz tempo".