First time a male Power Ranger is seen without a shirt, in this instance it's Zack.
This airs as season 1 episode 25 in Netflix.
For his Halloween costume as Sherlock Holmes, Billy includes a deerstalker cap. The hat is never actually mentioned in any of Arthur Conan Doyle's stories, and largely became associated with Holmes because of pop culture depictions of him; as described by Watson, Holmes was quite fashion-conscious and, given his status in London society, would not have made the faux pas of wearing such a garment.