“Barbenheimer” combined for a total of 21 nominations — a leading 13 for “Oppenheimer,” eight for “Barbie” — when Oscar nods were rolled out Tuesday morning. Yet “Barbie” director Greta Gerwig found herself on the outside looking in the race for best director, one of the few surprises from the nominations rollout. Other top nominees are “Poor Things” with 11 and “Killers of the Flower Moon” with 10. Here are five takeaways from Tuesday’s Oscar nominations. Strong showing for “Barbie,” except …”Barbie’s” eight nominations included best picture, America Ferrera for best supporting actress, Rya…