what she means:
There is no logical place in the fma manga/fma:b timeline for the events of 'Sacred Star of Milos' to happen. In the film, Al can transmute without a circle and Mustang still has all his subordinates, meaning it has to occur somewhere between episode 14 and episode 29. However, the events of these episodes happen nearly back-to-back. The only lapse in action that could allow for the movie to take place is between episodes 20 and 21, after Ed returns from Xerxes and before he and Al attempt to draw out the homunculi. But Winry is still in Central during this time, when in SSM, she shows up in Mustang's office as though only just arrived in town for a routine checkup with Ed. Her presence in Central from episodes 16 through 23 throws off any possibility of SSM taking place in that time. Though expressly marketed as taking place within the manga/fma:b adaption and not fma03, the only explanation is that SSM occurs in some alternate timeline.