A majority of the storyline is one giant continuity error.
It is a long established and often spoken of fact that Druitt was Jack the Ripper. It is also established that at the time of the Ripper murders Watson and Druitt were close friends and Watson never suspected his good friend and confidant. However this episode completely retcons all of that. Suddenly both Magnus and Watson are extremely suspicious of Druitt, except that he's apparently now (mostly) innocent. The real killer is a hitherto unmentioned abnormal, Spring-heeled Jack, an old acquaintance of Magnus's father and a serial killer.
While Helen is chasing Adam in the past, she is shooting at him with her semi-automatic pistol. During the chase, she has obviously shot all her ammo because the slide on her gun has locked back. But right after that she is shown firing at him again with the same gun. Now she could have reloaded her gun between the two scenes, but when we later see a pile of her possessions there are no spare clips for her gun.