When Bad Warlocks Go Good - S1-E18
Continuity mistake: Prue finds Brendan, as a warlock, over the corpse of Father Austin. He runs away and she pursues him. He insists that he "didn't hurt Father Austin. [He] found him like that." Prue counters, "Before or after you turned into a warlock?" His response is, "After. When I saw what [my brothers] did to him, I was crazed. The rage turned me into a warlock." So doesn't that mean that he found Father Austin before he turned into a warlock, not after? (00:17:55)
Suggested correction: He said after because Brendan has always been a warlock. He was born that way.
The Truth Is Out There... and It Hurts - S1-E8
Revealing mistake: When Phoebe asks Piper what she thinks of her boss, you can see that Holly's tattoo has been covered up, because that part of her wrist is darker than her skin. (00:17:15)
Suggested correction: Maybe Holly covered it up with makeup because she isn't supposed to have tattoos for her job? A lot of jobs still don't allow piercings and tattoos today but all those years ago it was even harsher.
There are multiple instances of covered tattoos during the early seasons. I noticed it the most on Alyssa's back tattoo.