Corrected entry: When Jake first arrives at the house of Miss Peregrine, she refers to him in pounds and speed of which he arrived. There, the movie takes place in Wales, in England. They use the metric system, not the imperial system. It should have been kg and kilometers.
Corrected entry: On a certain date in 2016, Jake enters Peregrine's Loop on September 3rd, 1943 where her children relive the same day over and over and all non-peculiars are completely unaware of the Loop. When the Loop closes and it becomes September 4th, 1943, the children, without re-entering 2016, travel by steamliner to London and enter a Loop set in a date six months prior to the date from which Jake entered Peregrine's 1943 Loop. The trouble is, this Loop did not exist in 1943, so it should have been inaccessible to the children.
Correction: The loops are accessible to any peculiars if it has been made. It doesn't matter the time period they enter it from.
Correction: There speaks someone who's never been to Britain. Even today speed is always given in miles per hour (including our speed limit signs) and plenty of people use pounds for weight instead of kg. Most importantly, this is set in 1943, well before Britain went metric.