Home for the Holidays - S11-E1
Other mistake: Only one set of prints were said to be on the garrote but in the last episode of season 10 Graham handles the garrote before handing it over to the murderer without wearing gloves. So there should have been 2 sets of prints.
Other mistake: James Pendrick shares his plans with Murdoch about how he is going to reach the orbit of the Earth by flying his own built rocket. However, earlier in the episode, Pendrick himself reveals that he is claustrophobic (extreme fear of confined places). Having such phobia would make his planned journey fundamentally impossible as he couldn't stay hermetically closed in the small rocket for long without suffering serious psychical damage.
Other mistake: Pendrick states that the rocket barrel is 70 metres long (deep). Despite that, Murdoch reaches the bottom in mere seconds, has enough light to see around and is even able to hear the others outside.
Murdoch Night in Canada - S5-E12
Other mistake: Murdoch sends Crabtree to buy six pumpkins, but when they test how tall the murderer might be, there are much more pumpkins can be seen.
Suggested correction: The show is set in the early 1900's, which is the early 20th century. By the time this event transpired, SOS would have been established as a universal distress signal.
The show starts in 1895 and by season 2, it was still the 19th century and before Germany adopted SOS in 1905.
Bishop73