positive reviews but sadly not a lot of audience attendance, Birds of Prey makes for an enjoyable return of Robbie's maniacal murderess-turned-antihero. It's a fan-favorite performance which is part of a larger tapestry of cool characters and multitudes of easter eggs for eagle-eyed DC Comics fans and aficionados.
A large number of easter eggs within Birds of Prey pertain to Harley's previous appearance in Suicide Squad. The animated intro rehashes her origin story from the Task Force X film, showing her meeting her abusive beau Mr. J (Jared Leto's Joker) and being subjected to the large vat of chemicals that bleach her skin. Birds of Prey arguably does Harley's origin better than Suicide Squad did, but it does so by repurposing certain bits of footage.
The Suicide Squad footage reused in Birds of Prey is Dr. Harleen Quinzel's transformation in the Harlequin of Hate's girlfriend at ACE Chemicals. In Suicide Squad, a neon-lit flashback sees him drop his lovesick psychologist into the same vat that made him the psycho he is before diving in himself. Birds of Prey takes this footage that's carefully edited to avoid showing the Joker's face.
Indeed, the entire movie doesn't show Jared Leto. This was a conscious choice by director Cathy Yan, who felt it unnecessary to feature the Joker too much. She did still want to use the existing footage of ACE Chemicals from Suicide Squad, however, to "[help] remind people what the significance of ACE chemicals is".
Suicide Squad was a financial hit, but with its low review scores and divisive status with many viewers - mostly because of its Boomerang on the wall of the police station.
Harley Quinn is best left to move on from rehashing old footage with Leto's Joker, to be able to move on with her own life and her own adventures. It's the entire raison d'être of Birds of Prey. She can however next be seen in James Gunn's The Suicide Squad reboot, which he is currently editing at home (due to the Coronavirus outbreak) for release in 2021.
