When Chandler and Street first meet Ellen, she sits at the table with her arms wide apart. In the next shot, they are close together.
Annie Chapman was Jack the Ripper's second victim, not fourth.
It stated that Liz Stride and Catharine Eddowes were both murdered in Mitre Square on the same night in 1888. They were both killed on the same night but only Eddowes was murdered in Mitre Square whereas Stride was killed in Berner Street.
The badges shown are for San Fransisco PD, not LAPD. Near the end of movie police are announcing the solving of the case with the help of LAPD and LA Sheriff Detectives, so badges worn by two lead detectives are correct as they are from LA SHeriff Detective Dept and their badges are star-shaped.
When Ben takes Ellen to the guest house to show her no one is there a light is on in the window. When the camera pulls out the light is off.