Character mistake: When asked if he had a job, Mason Sr proudly responded he just happened to have passed his second actuarial exam and that's what Mason could tell his mother. Mason Sr didn't seem to realise the first two actuarial exams are the easiest to pass, many aspiring actuaries have completed the first two exams by the time they earn Bachelor degrees, and will study for years for the remaining exams while employed full time. He wasn't anywhere near being an actuarialist and wasn't employed - yet bragged. (00:39:44)
Character mistake: During communication with ATC the co-pilot states their call sign followed by the read-back of ATC instructions. This order is incorrect. In reality a pilot or co-pilot reads back the instructions from ATC and then their call sign or tail number prior to ending their transmission.
Character mistake: Mitch states that he is Pisces then goes on to state that his birthday is 25th of March. The Pisces period goes from 19th February to 20th of March. Mitch would actually be Aries. (00:35:00 - 00:37:00)
Character mistake: When Jesperson imagines himself as a Mountie his uniform is completely wrong and is not even the right colour. As it was his ambition to join the force and he has photos of RCMP officers in his cab, it seems unlikely that he would imagine himself in a completely incorrect uniform.
Suggested correction: It's not a character mistake, for the reasons stated; it's a clear factual error from the filmmakers.
It's a character mistake since it's his imagination and, as you stated, it's not something the character would get wrong.
Character mistake: At the end of the movie, when Jaggu is listening to the sounds recorded by PK, the audio contains the question which she asked, "Tumhare planet pe sab aise hi hote, bade kan wale?" but does not contain the answer which PK gave, even though he was sitting right there. This seems to suggest that PK did not exist in the real world.
Character mistake: During the scene at the office of the University of Oxford, the Union Jack is hanged the opposite way from the proper position. (01:23:10)
Character mistake: When the police come to find Tammy, they say they are looking for a 2004 Cadillac Deville. It is a 1997 Seville in the movie.