When Billie goes to Henry's room, a ticking cuckoo clock can be seen in the background with the pendulum moving back and forth in a close-up shot of the two characters. In the very next shot, further away from the characters, the pendulum is no longer moving.
When Billie is singing to Henry, two white doves land on the windowsill. When they fly away, a string can be seen pulling on the leg of the dove on the left.