Just after the Doctor and Romana disembark from the Paris train, one of the passengers is looking directly at the camera and smiling as the train doors close.
When the Count removes his human mask to reveal his true alien identity, the actor's real skin can be seen under the green alien mask.
The human mask that Scarlioni wears to conceal his alien face would not allow him to see as the Jagaroth only have one eye that would be in the centre of a human forehead.
In the cafe, an artist is sketching Romana. However she is sat with her back to him by which makes this impossible - even though he draws a clock face in lieu of her real facial features.
At the end of the episode, there is a big reveal as Scarlioni tears off his false human face to show his true identity as the grotesque alien Scarroth. In doing so, he rips the human mask, but there was no reason for him to remove the mask at all at this point so he damaged it for nothing.
Just before the Doctor and Romana reach the postcard stand, he nearly trips on his long scarf.