The original ending had Shawn find Happy dying in the wheat field. The field was due to be harvested and Watson knew he couldn't cast someone in time so the ending was changed to Happy being found dead in the grounds of the high school he is seen entering. Feeling that this was rather flat he created the Tigger's Barn scene and 2 new characters. This ending went through 2 incarnations, one which would bring back Paul Michael McIntosh from Shawn's Dark Xmas (2012), but no one could be bothered committing. The fifth and final ending written, as filmed, is a combination of the second and fourth written endings.
Paul Michael McIntosh asked for more action after filming Shawn's Dark Xmas (2012) but as his character of Brooker was killed-off he had to be resurrected as someone new. The character of Paulie, Brooker's brother, was created but ultimately deleted and McIntosh changed his mind about appearing in any future movies and threatened legal action unless he was completely deleted from this film. The film languished in an unfinished state for almost 2 years before Andrew Preston stepped in as a reinvented version of the character.
The scene at Tigger's Barn is actually filmed inside an abandoned diary farm.
Implies that the plot of the never-completed "Shawn to the Rescue" still actually happened.
The beach scene at Carlingnose Point Wildlife Reserve was only partially filmed there. The beach was so heavily polluted that Shawn Watson opted to film on the much cleaner sand of Hound Point with key location shots inserted.