The name of the German policeman Koenig is mispronounced 'Keenig' throughout.
In the back-projection driving scenes, the steering-wheel movements bear no relation to what is seen out of the back window.
In the graveyard scenes, the 'torchlight' shone on the gravestone bears little relation to the angle of the torch, and is obviously made by a remote spotlight.
When the three main characters check into the hotel in Germany, the hotel's name (written in the old fashioned German script, Fraktur) is spelled 'Freiderich' instead of the correct 'Friedrich' (Frederick).
Frank keeps correcting the German detective about the "English" writers being Scottish by saying "Scotch," which the German humorously thinks he's suggesting a drink. While it was part of the accepted American vernacular in the 1950s time to refer to the ethnicity as Scotch, it was never correct. Scotch is and has always referred to the drink, Scottish the ethnicity.