I have done it twice on the line, pressing TOGA instead of AT disconnect, but the mistake is obvious and easy to correct. I have also done it the other way twice in the sim on single engine go-rounds, flying accurately enough because I tend to look through the FD anyway, using it more to confirm attitudes than to lead me, but didn't consciously recognise the mistake or even that the FD was sill in APP! Those who haven't made that mistake will. A total of four occurrences in 16 years is not atypical, from what I have seen, but having the FD in APP while believing it to be in TOGA could create quite a level of confusion. FMA cross checking helps, but you don't have the opportunity to do that as you press TOGA because you're too focused on the pitch and thrust inputs, config changes and getting away from the ground.