Okay so I looked it up. It appears the rules are different in the US than in Canada. The prosecution always goes first in closing statements regardless if the defense presents a case or not. The main difference is that the prosecution is given a chance for rebuttal of the defense closing statements. So in essence, the prosecution always goes first and last.
In Canada, there is only one closing statement per side. The order is determined by whether the defense presents evidence. If they do not, they get the final word. If they do, the prosecution gets the final word. Makes the decision to put lame defense witnesses like the two we saw here more difficult.
MOO