Factual error: When Bruce, Dick, and Aunt Harriet are looking at the globe, Bruce corrects Dick's mistake about Lima being the capitol of Ecuador and says "No, as you can see, I was right. It's the capitol of Peru." and points to the globe to show him. Based on the position of Europe facing the camera, he's actually pointing to somewhere in northern Canada. (00:02:35)
Other mistake: Not only can Caesar Romero's moustache can be seen, but the line between the white makeup and his skin on his neck. Also, when Robin's face came out of the clay, his mask was almost around his mouth. A moment later, the mask is back in place. Later, his face, mask, and body is spotless.
Other mistake: Batman throws himself into acid. Counting on acid-proof suits, Batman comes out unscathed, but his ropes didn't get burned off until he dipped the back into the acid. Also, even though he covered his face a moment, he came out with his face exposed, and undamaged, when it should have been burned.
Factual error: When Batgirl checks Batman's pulse, she states that his pulse is "three beats per minute." However, she only holds Batman's wrist for two seconds. There is no way she could have determined that pulse rate in so short a time. It is unlikely she could have detected even one heartbeat at that rate in two seconds.