'António Reis' really was on the 5th floor when cleaning the windows from the outside. And he does have vertigo.
This was the first film to use the then recently inaugurated Metro do Porto as filming location.
Eunice Bastos had an cirugical oral intervention on the previous day of the scene where she is slapped on the face, making it a really painful scene.
The fountain pen used by the CEO didn't really write anything. Albrecht Loops' real name is Alberto Lopes.