Complex sentence: He appeared in more than 25 Warner Brothers films during this time, including "Northern Pursuit", which starred Errol Flynn, "The Beast with Five Fingers", "The Very Thought of You", and "Objective, Burma!".
Split into simpler sentences: He appeared in more than 25 Warner Brothers films during this time, including "Northern Pursuit", which starred Errol Flynn. Other Warner Brothers productions that Alvin appeared in under his contract included "The Beast with Five Fingers", "The Very Thought of You", and "Objective, Burma!".