Complex sentence: Many of the Hollywood studios produced such films during the war, generally musicals, frequently with flimsy storylines, and with the specific intent of entertaining the troops overseas and civilians back home and to encourage fundraising--as well as to show the studios' patriotism.
Split into simpler sentences: Many of the Hollywood studios produced such films during the war. They were generally musicals, frequently with flimsy storylines, and had the specific intent of entertaining both the troops overseas and the civilians back home, as well as to encourage fundraising and to show the studios' patriotism.