Greg's position relative to the dead sheriff-lieutenant changes from the security camera view (close) to the movie camera view (further away).
Radio transmissions over earbuds cannot be heard by someone standing several feet away.
Washington has no highway patrol. It has a state patrol. The officer Greg and Lucy talk to in addition to wearing the wrong ranks also has the uniform of a deputy sheriff. Deputy sheriffs would not work out of a state patrol station.
The retreat is supposed to be in the US, but the helicopter has a Canadian registration (C-FJPH). Since the movie was filmed in Canada, they used a Canadian helicopter.
The charade of James and Serena being arrested ended too soon. The sheriff-lieutenant asked them to get the evidence. It did not matter if both of them went to get it, and it made no sense for him to say only one of them could go.
Lucy suggests laying low and going to the police in the morning. An attorney would know the importance of the police being contacted so as to rescue the other people in danger and to preserve evidence.
None of the armed gun thugs are involved in the final fight. All of them were not needed to control the other guests.
The sheriff wears contradicting ranks: three stars on his epaulets, and also a lieutenant bar on his collar.
After Alex inquires as to their medical background, Lucy says she is a lawyer and she knows her rights. Rights only apply to restraining the government, and since the retreat was not operated by the government, they would not apply. State and federal privacy laws would apply, not constitutional rights.
In the flashback, Lucy is walking in an open area outside a building and sees another woman kiss Greg, who is also in an open area. Greg recounts it as Lucy walking in an alley.