Another battling glitch
Both charged moves hit less than a second apart (but I swear the Outrage was slower). Timer continued counting down to 50. Could not flee, could not switch. Had to restart the game thrice and by then, the yellow spoofers had taken over the gym.
Seriously, GamePress should consider writing a guide about the known glitches in the PoGo (and workarounds where applicable).

Answers
Did you get an Error code to go with it, or was it just the game froze?
I had an issue a few days ago with trying to take down a gym from a few people using the GR defense. Got 1 of them out using the "Attack #1, Flee #2, Attack #1, Flee #2, Attack #1, Attack #2" strategy, then the game gave me "Error 29 - this Gym Battle is already finished" (the text may be different; I'm doing this from memory) when I tried to Attack #2. Restarted the game, no change. Restarted the phone, no change. Had to wait 10 minutes to continue battling the gym.
Rather annoying.
I got this yesterday as 1) the only trainer attacking the gym, 2) reasonably stable GPS signal, 3) no manually exiting between battles. I was locked out and had to abandon the attempt to take down the gym despite it being nearly dead. I haven't found a workaround for reversing the lockout, although it sometimes will only take a couple of iterations of trying to restart the battle for it to allow me to resume battling (i.e. it doesn't require 10 minutes).
I've also gotten this error when using that exploit, or after manually exiting gym battles in an attempt to knock Pokemon out one at a time. It's incredible that they haven't patched it at this point because it has been a consistent feature of gym battling for as long as I can remember, and it sucks.