On Jeffrey's office wall is a photo of Gilbert R. Hill, who played Inspector Todd in the first three films (and whose character was killed in Le Flic de Beverly Hills 3 (1994)). Hill passed away in 2016.
When Bobby Abbott (Joseph Gordon-Levitt) goes over Axel's three other cases in Beverly Hills, he mentions that the third "wasn't his finest hour", which is referencing Le Flic de Beverly Hills 3 (1994), that Eddie Murphy despised and is the lowest rated of the series.
Talking about making the film to People magazine, Eddie Murphy said, "It was a hard one. I did Axel Foley when I was in my 20s. I am not in my 20s anymore. It was an action movie. So it was a rough one. But we got through it." For the record, Murphy was 23 when he did Le Flic de Beverly Hills (1984) and is now 63 in Axel F.