When Gustav phones Dienstag, Dienstag's sister Frieda, who Dienstag has locked out of the room, is reaching in through a window and has picked the handset off the ringing phone when Dienstag seizes her hand at 0:38:05, but an insert shot at 0:38:07 shows the handset is still setting on the phone which is still ringing.
Grundeis offers Emil a jelly bean on the bus. Jelly beans are an American confection. They didn't exist in Germany at the time.
Emil is sent to Berlin on a bus, which is how Americans traveled in 1964. In Germany, he would unquestionably have gone by train.
The seats are numbered on the bus Emil takes from Neustadt to Berlin. At 0:04:38 the number 13 is on the back of Emil's seat. At 0:04:54 the number 1 is on the toddler's seat in front of Emil. At 0:05:13 the numbers 1 and 2 are on the empty window seat immediately behind the driver and the aisle seat to its right where August Grundeis is initially seated. Apparently, the toddler's side of its interaction with Emil were shot in the front of the bus.
When Mueller tells Grundeis he has "two days" to complete the job, he holds up his index and middle finger, American-style. Germans count two with the thumb and forefinger.