In the novel it was the V2 that killed Katje´s little brother Louis (p. 546), in reality on dec. 16, 1944 (on the 18th GR begins) the REX-cinema in Antwerp was hit, 561 dead. My source (DIE ZEIT Nr. 29, July 16, 1993, p. 54) says nothing about the film being shown but you´re idea of course is great and absolutely probable. Otto