Continuity mistake: At the lab, when Young Barry collapses, his head lies on a white tile and his hair is all messed. A shot later it lies on a coloured tile and it's not messed.
Revealing mistake: When the Barrys cross through the glass door, for a couple of shots, Young Barry's face is replaced with a non-realistic CGI face with features that don't match the face contour at all.
Continuity mistake: Young Barry forces Old Barry into eating broccoli, which he does in large bites. When Young retrieves the broccoli, it's uneaten.
Continuity mistake: When the movie begins, the way the barista holds his notepad changes between shots. (00:01:07)
Continuity mistake: When Batman and Falcone are pulled up, the case with the virus is open (you can see the bottles). When they are on the bridge, suddenly the case is closed. (00:12:29 - 00:13:00)
Continuity mistake: When Bruce is explaining about time travel issues to the Barries, the amount of sauce on the spaghetti changes between shots. The spaghetti in the bowl shifts as well, most noticeably when there's some right up on the lip of the bowl close to Bruce, which then disappears from another angle.
Continuity mistake: During the post-credits scene, after Arthur falls on the puddle, there's a leaf on the pavement in front. When he turns around begging for beer, the leaf disappears, only to reappear a shot later.
Answer: Some possible reasons gleaned from the Internet: Filmmakers wanted a different vision of Supergirl to reflect a darker, grittier personality and to show her refugee-like experience. Her dark short hair symbolizes her harsher journey from her home world. Also, it gives her a more androgynous look, reflecting both her feminine and masculine traits. Adopting a radically different look for an established character also shakes up viewers' expectations and generates more publicity and interest in the film.
raywest ★