Other mistake: When the whole crew travels to New York in that truck full of fish, when they arrive at the base, before opening the garage, there is a surveillance camera right in front of them above the door. God's Eye could easily spot them through that camera. (00:56:44)
Other mistake: When Dom and Cipher break into Mr Nobody's base, they use "the latest in concussion grenade technology which scrambles all senses and lasts an hour" which would include vision and is reflected as such. 2 min later Letty and Hobbs are able to see the kiss Cipher gives Dom.
Other mistake: When the team get off the sub they leave the hatch open. That can only be closed manually, so the sub would have simply sunk within a few minutes of submerging.
Answer: Well, we know that Owen Shaw was once an SAS soldier. Deckard Shaw has a file in this movie that reveals he saved a team he was part of and saved some hostages in the past. When Deckard Shaw refused to do the job Cypher wanted him to do in Furious 6 to steal the nightshade device, Cypher then went after Owen Shaw and convinced him to do the job. Cypher is the true mastermind behind everything that has happened in Furious 6, 7 and 8. So, maybe the Shaw brothers were good guys at a time before Cypher came along.