"Screwed" could qualify as an anachronism. Using "screw" like that started some time after screws started to be used in Europe. I'd imagine that the term's slang usage increased as use of actual screws became more common. My super-quick research indicates that using "screw" as slang began in the 16-1700s, but AFAIK it didn't show up often until the late 19th century (soon after screws became readily available to the public). If your society uses screws and has for a while, it's totally cool to use the term as slang.
"D*** straight" is fine to me. I can't see many people using it in fantasy, though Zelazny did use similar phrases in the Amber series. His character was from mid 20th century America
. Your setting (if we're talking about Crystalheart here) is gritty enough that I can see people talking like that. I'm guessing that I haven't seen it often because my experience with the genre has been primarily in older high fantasy. The term consists of two pretty common and old words, so I'm not going to even try to find history for it. "Straight" has been used in tons of different ways for ages and people have sworn for just as long, so it seems to me a distinct possibility that even someone from 10th century England used the phrase.
I'm not sure if it's practical to research every slang term, but if you get a comment about it make sure to double-check the term's history. Obviously as writers we don't have the time to double-check the history of every word we use. Well, maybe we do, but I wouldn't like to spend all of my time "checking" (another anachronism) my writing.
An interesting side note: I found that "putting your X on the line" is related to the use of X as a symbol for a kiss, dating back to the Roman Empire. Crazy times.