The Immaculate Conception (note that this is not the same thing as the Virgin Birth, although people often confuse them)
Jonah getting swallowed by a whale (it was a fish, or possibly two fish)
Three wise men (there were three gifts and an unspecified number of wise men)
Anything indicating that Satan rules hell, that hell has multiple layers, or that there are specific punishments for specific sins
Any mention of leprosy aka Hansen's disease (the condition the Septuagint translates as λεπρός has completely different symptoms from the condition that came to be known as leprosy in English)
Isaac being a child during his near-sacrifice
And some Jewish specific ones for the Tanakh, because we can’t let Christians have all the fun:
Yitro converting to Judaism
Avraham smashing his father’s idols
Moshe having a stutter due to burning his mouth on hot coals
Any mention of the lulav and etrog being shaken on Sukkot (Vayikra says to collect the Four Species, but nowhere in the written Tanakh are we actually told what to do with them)
Literally anything about Hanukkah (Sefer HaMakabim is not canonical)