Matt Berry, who plays Douglas Reynholm, is only nine years younger than Christopher Morris, who plays his father, Denholm Reynholm.
At around 1 minute as Denholm is speaking to his staff, a spider can be seen between him and the camera quickly ascending up its web. It starts at the bottom right half of the screen and up to the top right corner from Denholm's brown jacket ascending over his left shoulder.
The painting that Douglas has on his office wall behind his chair (the one with the many vertical and horizontal line segments) is a print of one of Piet Mondrian's abstract paintings of a tree (the line segments represent branches and twigs).
Roy's T-Shirt with the "I see dumb people" caption is a geekish reference to The Sixth Sense (1999) whose catch phrase is "I see dead people".