The film was produced on a $40 million budget and was filmed back to back with its sequel, "Part III". Filming began in February 1989 after two years were spent building the sets and writing the scripts. Two actors from the first film, Crispin Glover and Claudia Wells, did not return; Wells's character Jennifer Parker was recast with Elisabeth Shue in the role, while Glover's character, George McFly, was not only minimized in the plot but also was obscured and portrayed by Jeffrey Weissman in heavy make-up. Glover successfully sued Zemeckis and Gale, changing how producers can deal with the departure and replacement of actors in a role. "Back to the Future Part II" was also a ground-breaking project for visual effects studio Industrial Light & Magic (ILM): In addition to digital compositing, ILM used the VistaGlide motion control camera system, which allowed an actor to portray multiple characters simultaneously on-screen without sacrificing camera movement.