Question about 103 "Lord Snow"

[Jack Bauer 24]

Why was Cersei mad at Jaime for sending the assassin to kill Bran. Didn't she suggest early that he needed to take care of the situation?

And at the end when Ned was watching Arya train with Strip, why did his smile turn to concern and there was audio of swords clashing in the background?

[Needle]

Ned probably had a flashback to Robert's Rebellion, to his sister Lyanna. Many characters agree that Arya is very much like Lyanna, both in appearance and personality. Ned was happy at first, watching his wild daughter training at something she likes, and enjoying it too. But then suddenly he is reminded of the Tower of Joy, and the battles that occured because of it. The most popular quote about Lyanna is "Beautiful, and willful, and dead before her time", not to mention this quote comes from Ned talking to Arya.
Knowing how wild and fierce Arya is, he might've feared she'll meet the same early fate as his sister.

[Dornish Gourmand]

He was upset because of the lack of season 7 episode titles and details concerning the premiere.

[Flayed Potatoes]

Why was Cersei mad at Jaime for sending the assassin to kill Bran. Didn't she suggest early that he needed to take care of the situation?

And at the end when Ned was watching Arya train with Strip, why did his smile turn to concern and there was audio of swords clashing in the background?

1. I don't know. Maybe because it would seem too obvious they were involved or were trying to hide something.

2. PTSD from Robert's Rebellion

[Joel Needs a Car]

Why was Cersei mad at Jaime for sending the assassin to kill Bran. Didn't she suggest early that he needed to take care of the situation?

And at the end when Ned was watching Arya train with Strip, why did his smile turn to concern and there was audio of swords clashing in the background?

1. I don't know. Maybe because it would seem too obvious they were involved or were trying to hide something.

Exactly this, if there were already suspicions that Bran's fall was no accident then a clear attempt on his life would tend to confirm that.

[Jack Bauer 24]

But she told Jaime to take care of it. What else would she have wanted him to do?

[Flayed Potatoes]

But she told Jaime to take care of it. What else would she have wanted him to do?

Probably take care of it in a more discreet way and actually succeed.