In the opening when Freddy is heading towards his crash with the tree, his suit changes from striped to solid to striped to solid.
Although Baxter's motorbike is a correct model for the 1920s/30s, its tax disc is dated April 1966.
Baxter announces that he has reclassified Emsworth's collection of marbles by "size, left to right," and by "colour spectrum, right to left." One or the other ought to be top to bottom (or bottom to top).