Laboring away quietly in the basement of the Duluth Depot, the Underground is busy making theater. In recent weeks, we've featured productions like Green Day's American Idiot and Gilbert and Sullivan's Ruddigore. Now the 12th Annual Short Shorts Film Festival returns with another crop of entries: all five minutes long or less and all family-friendly. But this is not a quaint little local event; the festival features submissions from Asia, Europe, Israel and South America, not to mention states all over the US.