Is there significance to this frame from the season 2 opening? Pictured are 6 members from the 104th training regimen, but they seem somewhat randomly selected. 



At least, that is until:


   We find out that the two on the left are the armoured and colossal titans, and then Eren, who is also a titan, appears to be center-left.


Is there some significance or implication to this picture?
The significance is more than likely representing the lyrics of the song. When comparing the actual intro here and the translated lyrics here, the lyrics during that moment of the intro are


  Dedicate! Dedicate! Dedicate your heart!