For continuity's sake over the course of a long shoot, Producer and Director Sir Carol Reed restricted Bobby Henrey's access to the cake trolley during tea breaks on-set so he wouldn't gain weight. Continuity was also the issue in Reed's only disagreement with Madeleine Henrey. A scene with Bobby running up the stairs was left half-completed at the end of the week's shooting on a Friday evening. Over the weekend, Madeleine decided the boy needed a haircut, and when he returned to the set on Monday, it was impossible to match the remaining shots they needed to the ones taken a few days before. The Make-up Department tried attaching hair pieces to him, but it didn't look right. Reed was furious and had no choice but to rearrange the shooting schedule to complete the stair scene after Bobby's hair grew out. "It's the most expensive haircut in the world!" Reed groused. "Thousands of pounds! That's what it will cost!" The incident was the only delay in an otherwise smooth shoot, which ended up completing on schedule.
The biggest challenge was getting such an amazing central performance out of Bobby Henrey, who had no experience, or much acting ability, yet was on-screen almost the entire movie. Assistant Director Guy Hamilton noted that the boy "couldn't act his way out of a paper bag" and had "the attention span of a demented flea." He also remarked that things got more difficult when Bobby got bored after twelve to fourteen weeks of shooting.
Despite Phillipe's (Bobby Henrey's) hatred of Mrs. Baines, Henrey's favorite person on-set was the actress who played her, Sonia Dresdel.
Sir Carol Reed used all kinds of tricks to get the results he wanted. In the opening scene, when Phillipe (Bobby Henrey) is supposed to be looking over the banister at Baines (Sir Ralph Richardson) with affection and interest, Reed had a magician perform for Henrey off-camera to get the facial expression he needed.
Because Bobby Henrey was not used to working with other actors, Sir Carol Reed had to shoot him primarily in reaction shots. He also had to keep his dialogue down to small bits, so the movie was planned to be very cut heavy. In its one hour and thirty-five minute running time, there are more than one thousand edits.