When the crew is shown the garage of all of the cars including the army tank, you can see Paul Walker's GTR that his character drove in Dangereux 7 (2015) up on top of one of the three-tier car racks. A subtle tribute to the late actor.
A week before filming ended, Dwayne Johnson posted an infamous message on Instagram, confirming that the production had endured its share of on-set frictions: "This is my final week of shooting #FastAndFurious8. There's no other series that gets my blood boiling more than this one. An incredible hard working crew. Universal has been great partners as well. My female co-stars are always amazing and I love 'em. My male co-stars however are a different story. Some conduct themselves as stand up men and true professionals, while others don't. The ones that don't are too chicken shit to do anything about it anyway. Candy asses. When you watch this movie next April and it seems like I'm not acting in some of these scenes and my blood is legit boiling - you're right. Bottom line is it'll play great for the movie and fits this Hobbs character that's embedded in my DNA extremely well. The producer in me is happy about this part. Final week on Fast 8 and I'll finish strong. ;/ #IcemanCometh #F8 #ZeroToleranceForCandyAsses". The post came after co-star and executive producer Vin Diesel reportedly cancelled some of Johnson's planned scenes at the last minute. On several occasions, Diesel had also reportedly refused to show up on-set as he was scheduled, leaving hundreds of cast, crew, and extras waiting on-set for him for more than six hours. Diesel confronted Johnson in a secret meeting one day after Dwayne's message was posted on-line. Johnson later told The Hollywood Reporter that the meeting cleared up a few things. He confirmed that he and Diesel did not shoot scenes together because of "a fundamental difference in philosophies on how we approach filmmaking and collaborating", but that he was "grateful for that clarity". Although he did not provide details, it was later revealed that the announcement of Johnson's spin-off movie Rapides et dangereux présentent Hobbs et Shaw (2019) was one of the main reasons for Diesel's behavior (as it would split up the series, and delay Rapides et dangereux 9: La Saga (2021)). Johnson stated that he would probably pass on Fast & Furious 9, but wished Diesel "all the best and I harbor no ill will there, just because of the clarity we have. Actually, you can erase that last part about 'no ill will.' We'll just keep it with the clarity".
In one argument between Hobbs and Shaw, Dwayne Johnson decided to ad-lib and came up with a line about knocking Shaw's teeth so far down his throat, he'd need to stick a toothbrush up his ass to brush them. Jason Statham was so amused by the ad-lib that he broke character and started laughing. That's the take that was used in the film.
When Mr. Nobody (Kurt Russell) explains the "top 10 most wanted" list, and that Roman (Tyrese Gibson) was number 11, he says people in the room are numbers 6, 8, 9, and 10. The missing number 7 is a tribute to Paul Walker, who died during production of Dangereux 7 (2015). His character, Brian O'Conner, is now out of the line.
Paul Walker's character, Brian O'Conner used to drive Japanese imports. His replacement, Little Nobody (Scott Eastwood), who was his close friend in real life, also drives these type of cars (Subaru BRZ and Subaru Impreza WRX STi) in this movie. This indicates a tribute to the late Paul Walker from Scott, as these types of cars were his favorite in the Fast and Furious films, as Brian O'Conner and in real life.