user18369: 
How is this checkmate? The King isn't even in check! Am I missing something, or did the chess app goof up?

user12873: If the app first displayed checkmate in that position, then it miscalculated.
But as Phonon noted, the app could have displayed checkmate in a previous (future) position, and then you went back a few moves. In that case it's not a miscalculation per se, but just a bug in the UI.

18369: <p><img src="https://i.stack.imgur.com/hdMhT.jpg" alt="enter image description here"></p>

<p>How is this checkmate? The King isn't even in check! Am I missing something, or did the chess app goof up?</p>
 12873: <p>If the app first displayed checkmate in that position, then it miscalculated.</p>

<p>But as Phonon noted, the app could have displayed checkmate in a previous (future) position, and then you went back a few moves. In that case it's not a miscalculation per se, but just a bug in the UI.</p>
