Other mistake: When Dom and Brian are speeding alongside the train, in some shots Brian's shirt is billowing, in others it's not, despite travelling extremely fast and being outside. (00:15:35)
Other mistake: In the scene where Toretto and Hobbs are fighting, the fight is so violent that Toretto's eyes are run through glass, faces are smashed into concrete and beat endlessly. Yet when the fight is over, the next scene shows both with not so much as a mark on their faces. (01:28:00)
Other mistake: Throughout the vault scene, Brian and Dom have black cars. Several times they bump into each other without getting any damage. (01:47:10)
Other mistake: Throughout the entire chase scene at the end, the vault creates sparks on the road. Yet when they get to the bridge, no sparks appear. This cannot be due to the vault being empty at this point, as the vault itself is 10 tonnes, as mentioned earlier in the film. (01:49:00)
Other mistake: Hobbs asks to see all footage from "in and around Waterloo station." The technician is then asked to "bring up cameras 58 through 62." 5 cameras to cover the entirety of that area is laughable.
Other mistake: In the final chase scene with the vault when Brian is in reverse and Dom is pulling, Brian stops to take out the two bikers. The vault stops too but in Dom would still be pulling it since there was no communication, plus the inertia of the vault would have dragged Brian or smashed Dom.
Answer: Hobbs doesn't see that scene, though he probably does guess part of what happened - ie. that they swapped the vaults. The scene is played as a reveal for us, the audience, to show us how the vault that is supposed to be full of money is now suddenly empty.
roboc