There is an episode in Princess Zhu Huan in which the swallow thinks that Wei Zijin's martial arts can't get up and down under the tree, and then he is saved by Saiwei Saiguang. Which episode is it?

You have mixed up the two plots of land. The episode you want is the first episode 15. Swallows teach gold locks, but whips can't be taken off when they are hung on trees. Swallows climb trees, and Erkang brings Gao Yuanda (not Saiwei Saiguang). Erkang takes off his whip, and the swallow falls (hopeless). Another story you mixed up should be the rules that Sister Rong taught swallows. Swallow doesn't want to learn, but she can't get off the tree. The emperor caught her and ordered Saiwei Saiguang to save her ~ This is the seventh episode of the first film.