Fridge Brilliance: Sonic loses his Boost, but gets back his Spin Dash. In Sonic Generations, Sonic taught his past self his Air Dash; conversely, meeting his past self has reminded Sonic of the Spin Dash!
Fridge Horror: When the Deadly Six drain the life out of the planet, Amy and Knuckles lose their lives as well. Then you remember that not only is this affecting the whole planet, but is very likely affecting all of Sonic's friends there as well. Shadow, Rouge, Professor Pickle, Vanilla, Cream... who's to say the Gaias aren't affected as well?