The way they showed her walking, and the train that was opposite/to the left of her appeared, disappeared and reappeared, it gave the impression that it was either an extremely long walk, took an extremely long time to walk, or some of it was actually re-shot at a totally different time (even day?).
If the latter, I wonder how they'd get permission to stop trains just to do a short piece to camera when there probably was no bag that time.
I'm still wondering if the whole dropped bag wasn't set up anyway. Given my feeling that the episode was all about showing EC in the best light, the cynic in me says that some of these situations might be well prepared and planned in advance. Get a 'member of the public' (read: runner, mate of someone from the production company etc) to drop a bag, then prepare the closing of the line and the walking sequence etc.
I wonder if there's a whole list of things that EC wanted to convey as being things it has to deal with on a day-to-day basis, and it was easier to stage them than simply hope these things happened when filming took place.
If we can see they showed footage on different days to support the narrative, they can't have actually been filming that much and would have had little choice but to fiddle things.
That would make this series more akin to the faux reality shows that now adorn our screens, and seem to be perfectly acceptable forms of entertainment.