After Ben is dead, it is suddenly morning again, when a few moments before that is was still pitch black outside.
When Lisa opens the first poem she receives, there are clearly three stanzas. However, when she sets it down while talking on the telephone that evening, there are now only two stanzas on the piece of paper. She is shown with the same poem later in the film and there are now three stanzas again.
When Lisa reads out the poem in the final scene, she gets the first two lines in the wrong order.