Factual error: When Lucy jumps off the platform to save Peter, and is trying to wake him, the oncoming train blows its whistle. However, the L-trains/subways in Chicago do not have whistles like ground locomotives do.
When Lucy and Jack are walking along the river, a long shot shows them approaching a lamppost with a kissing couple. In the next shot, they pass the lamppost but there is no one there. They finally pass the couple at the next lamppost.