The main Berlinale campus at Potsdamer Platz is easily reached from the Miniloft Mitte apartments. Take the S-Bahn (Nordbahnhof to Potsdamer Platz, door-to-door travel time 20 minutes), or a "Kurzstrecke" (short trip) taxi, which costs 4 EUR. Please note that the discounted short trip price is only valid for taxis hailed on the street – go around the corner to Luisenstrasse and pick up a taxi heading south. There are always plenty of taxis.
Walking time is 30 minutes.