Other mistake: Director Krennic is shorter than Tarkin in their scene together. Krennic comes up to Tarkin's ears at best. Krennic is also shown to be about the same amount shorter than Darth Vader, roughly coming up to Vader's ears as well. But as shown in A New Hope, Tarkin is considerably shorter than Darth Vader. So by what was shown in A New Hope, Krennic should be much shorter, perhaps coming up to Vader's chest.
Continuity mistake: When Vader appears at the end, the amount of rebel soldiers facing him changes throughout the scene from about 8-12 as Vader makes his way through them.
Continuity mistake: When K is at the control panel he shoots two stormtroopers to his right. He then says stardust and moves his aim slightly to his left and shoots the same two stormtroopers again - the first two stormtroopers have disappeared from the floor.
Answer: Yes. They were on their way to the starport when they were encountered. They left the planet a short while later, before the Death Star attack.