Hone made aishite? Akane koi o fukuzatsu kossetsu - S1-E5
Plot hole: Dr. Tofu is able to tell that Ranma was hit by a softball (he says something about the marks like he actually sees them), but Ranma's wound is still covered by the bandage, that he'll remove in the next episode. This is linked to a larger mistake in the following episode. (00:19:55)
Gakkou wa senjouda! Taiketsu Ryouma vs Ryouga - S1-E8
Plot hole: In his flashback, Ryoga emerges from the sea and faints on the beach of Okinawa. That's quite the big oversight in plot, since Ryoga, as revealed in the following episode, has a curse similar to Ranma's and he would have emerged from the sea in his animal form and not as 'himself'. (00:07:20)
Sukeban no me ni namida? Rûru muyou no kakutou shintaisou kecchaku - S1-E13
Plot hole: In the anime, Ranma commits an unsanctioned violation of the rules when she throws Kodachi out of the ring (the time when she gets saved from her schoolmates); she in fact grabs Kodachi's arms using legs and feet, and projects her. In the original manga there is no such mistake; Ranma used her feet to spin the club Kodachi was holding, so was not throwing Kodachi directly, but using the tool just as the rules say. (00:15:45)