The film is pretty accurate with regards to how he currency exchange happened, although the plot demands that the characters were not aware of the deadline, which was stretching credibility. The currency exchange was a highly publicized event in the Wende and a subject of much public commentary.

As part of the unification process, the West Germans created a very generous currency reform in which individuals could exchange Ostmarks (DDM) for Deutsche Marks (DM) on a 1:1 ratio. The East Germans could exchange up 4000 DDMs at this highly favorable ratio; savings over 4000 DDMs could be exchanged at a 2:1 ratio. To discourage speculation, DDMs acquired before shortly before unification had an exchange rate of 3:1. GDR pensions were simply converted over to DM at a 1:1 ratio and debts like housing loans were 2:1. There was a window in which East Germans could convert their savings. The logic of the Kohl government was that a shock economic transition would hasten the economic reintegration of the two Germanies. The Bundesbank was generally opposed to such a measure, but the political imperative of swift unification of the economy overrode more economically sound alternatives. There were not a few critics of Kohl then or since who argued that the equitable exchange rate was an attempt to grease the acceptance of unification by the GDR's population so as not to interrupt the increasing inertia of unification.

In a sense, the East Germans did lose all of their money, but in return they gained a far more valuable currency. The DDM could only be legally spent within the GDR and its unofficial exchange rate with the DM prior to unification fluctuated in the black market, hovering around 5:1 or worse. The overall success of the currency reform is a bit mixed. On one hand, it did swiftly reintegrate the country economically and it forestalled any political embarrassments such as pauperizing pensioners. However, part of the currency reform was it also converted GDR wages from DDM to DM on a 1:1 basis. This had the effect of pricing the eastern half of Germany out of the market for a good decade since the former East Germany had a dilapidated economic infrastructure that made it much more inefficient compared to the west. There were hopes that the currency reform of 1990 would have the same results as the 1948 currency reform in the FRG, but these came to naught.

Sources

Berghoff, Hartmut, and Uta A. Balbier. The East German Economy, 1945-2010: Falling Behind or Catching Up?. Cambridge: Cambridge University Press, 2014.

Zatlin, Jonathan R. The Currency of Socialism: Money and Political Culture in East Germany. New York, Cambridge, 2009.