When Fynch and Gurney are talking in Gurney's office, part of Gurney's dialogue is obviously dubbed by another person as the tone is completely different from the actor's voice.There's no obvious reason such as any profanity so it can't be determined why.Also the dubbing is when the actor is not on camera to see a lip mismatch.
In early scenes in Gurney's office with Fynch and the maintenance technician, a clock and pennant hang on the wall behind the desk next to the drawing of the roller coaster. In later scenes, the clock and pennant are gone.
This was clearly filmed in winter, given the cold weather and bare trees, yet all the shots of the rides in action to establish setting are in hot weather with the trees green and full.
This story is supposed to occur around Washington, D.C., but the Californian mountains are often seen in the distance.
When he's skulking around the tunnels, Gurney's brother limps like he can barely move. But when he's trying to get away from Wonder Woman in the park, he runs and jumps like an obstacle course champion.