Continuity mistake: After Young Barry's mom grabs him by the shirt, the camera angle shows their broken down car by the road. A few shots later as Barry takes off running towards the gas station, the distance between the road and the car has increased by about double. The patches of grass around the car also change around between shots. (00:00:55)
Continuity mistake: When Wonder Woman is sharpening her sword, the direction of the sharpener changes between shots. (00:33:45)
Continuity mistake: When Batman starts shooting at the heat vision guy, an orange car is behind him. The shot cuts and he is suddenly standing with the car on his left. (01:01:45)
Continuity mistake: Barry places a bouquet of flowers on his mother's grave at the end of the movie. The bouquet is upwards to start with, but lying on the ground when the shot cuts. (01:15:25)
Continuity mistake: Aquaman coughs up blood after he is stabbed by Wonder Woman. Some blood goes on his chin. Throughout the rest of this scene, the blood on his chin keeps going from the right side to the left side of his chin. (01:10:25)
Continuity mistake: Lois hides under a purple car. It becomes red after a beast walks over the bridge. (00:39:15 - 00:39:45)
Continuity mistake: The Flash trips in a field with loads of cacti. One of them changes in appearance between shots. There is also a two foot tall cactus with no branches next to it that disappears. (00:43:10)
Continuity mistake: The Flash is back at Wayne Manor with Batman, after regaining his powers. In the wide shot of the Manor's interior, the windows are about 5 feet in height. The next shot shows the windows now only about two and a half feet in height. (00:45:05)
Answer: Flash couldn't travel through time later in the movie not because Zoom was alive but because Zoom was also tapping into the Speed Force, preventing Flash from gathering enough of the Speed Force to break the Time Barrier. When Flash originally went back in time it's likely because Zoom was in custody, therefore not tapping into the Speed Force at that time.