19. Nicht Stören
Whilst Indy is using his correctly proportioned Staff of Ra to locate the Well of the Souls at Tanis, the beam of sunlight that is revealing the resting place of the Ark of the Covenant to him passes over a building in a model of the city that is marked in red paint as "nicht stören" - the German phrase for "do not disturb".
Whilst this phrase immediately conjures up images of a sign hooked over a hotel door handle, on reflection it may hold more sinister connotations. For instance, it could be that there is something in this particular building that even the Nazis do not want to tamper with.
But what on Earth could be worse than a golden chest which, when opened, sweeps away entire armies and can even level mountains? Perhaps it is best not to know, but it would make a great concept for a sequel. After all, later Indiana Jones films have shown that they are perfectly willing to exploit what made Raiders great.
Alternatively, of course, it could purely be a place that Pharaoh Shishak wished to keep, well - you know - private! If so, it's kind of nice that the Nazis chose to respect that, really...