When Ian Eastman says that Felix was not to take off the rope around his neck or to touch it, Felix is shown with his hands tied behind his back. This would have prevented Felix from touching the rope at all, and would never have indicated a suicide rather than a murder because no one could hang himself once his hands had been tied behind him.
When the trailer is set on fire and the door blocked, the occupant wakes up soon thereafter. Despite numerous windows being present in the trailer, the occupant fails to break any of them out to escape.
During the rehearsal for the retaking of the vows, the vicar tells Mrs. Barnaby that the service would start with her and her husband walking down the aisle. He then indicates the central passage of the church. Although this is commonly called the aisle (people speak of the bride "walking down the aisle"), the vicar would certainly know that the central passage is called the "nave". The aisle is the side passage of the church.