At the Shell Town Marine base, in addition to the Wanted posters of Alvida and Buggy, there are posters of Bellamy, Jango, Foxy and Cavendish.
In the flashback scene where Shanks treats Luffy's injury in Makino's Bar, the melody of the pirate song "Bink's Sake" is playing in the background.
Even though Zoro's fight against Mr. 7 was not shown in either the manga or the anime, it is canon. In the manga and anime, Zoro talks about this fight and the Baroque Works recruitment attempt. Oda was later asked by fans what Mr. 7 would have looked like. He simply scribbled a person with high hair and the number 7 on his face. These details were eventually carried over into the live action series.
During the opening with Gol D. Rogers, a young Shanks, Mihawk, Smoker, and a young Crocodile, who is shown as female instead of male, are in the crowd. This is actually based on the fan theory that Crocodile was once female.
Luffy accidentally burns down Alvida's ship when he punches her into the horizon, explaining how she lost her ship and crew in a more logical manner.