Other mistake: When Earl's wife is pulling into her garage after picking up the medication, wet tyre marks (presumably from previous takes) are visible on the garage floor.
Other mistake: When the nurse opens the door you can see the big dog looking at the camera; it does this a few times until someone calls him away. Once when the door is opened you can see the person coming in giving a treat to the dog.
Other mistake: In the end credits, there is a character in the cast referred to as "pedistrian #2." Clearly this is a typo, where an I is used instead of the second E and should have been spelled "pedestrian #2." (03:03:52)
Other mistake: When the narrator is detailing the murder of Sir Edmund William Godfrey, the third murderer is referred to as Daniel Hill, played by Neil Flynn. In the end credits, Neil Flynn is credited as playing Stanley Berry, and not Daniel Hill. (00:00:55 - 03:03:40)
Answer: It's much debated the exact meaning, but it's kind of a reference saying that seemingly impossible things do happen. As we see later in the film, people stuck in similarly impossible situations might just have a chance of getting out of them.
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