Ah, thanks all. I was put off by the fact that:

my @things = $q->param('t') || $q->param('things');
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didn't DWIM, as the || puts each method call in scalar context. As an aside, how could one force list context for the evaluation of each of those method calls? With my imaginary list counterpart to scalar:

my @things = list($q->param('t')) || list($q->param('things'));
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