Occasional mild sexual references. A major character is revealed to have a child out of wedlock. In another episode, a character asks another if Eureka is able "to do it," causing him to be hit.

The main cast of characters will sometimes mention the "changes" Renton is experiencing at the time.

In another episode Renton picks up a magazine that is obviously sex-oriented, although nothing really explicit is shown. Two of the other male characters then try to help him by providing him more magazines, this is quickly (?) by the other characters. Holland is shown on rare occasions reading a magazine, the front cover shows a naked woman, nudity is somewhat shown.

Talho, Eureka, Hilda, and Gidget wear mildly revealing clothes, however it is never focused on since the show doesn't really have fan service. This show is meant to be romantic, and thus romantic relationships are often discussed, there are no sex scenes.

Violence isn't common. But when it does things do get somewhat violent. It is pretty surprising when it does happen since it is so infrequent. Renton and Holland get into fights multiple times in the first half of the series, none are particularly violent. Mech battles appear here and there, a part that could be a creepy factor for some is that the mechs can bleed when injured.

In one episode, Renton, while piloting a mech (LFO), goes into battle and relentlessly beats several of the other mechs leaving blood on the floor, and more disturbingly, we briefly see an arm in the pool of blood, causing Renton to feel bad about what he just did. In another episode, a woman sees her husband dead on the floor, she then kisses him on the floor but leaves a bomb, after the bomb explodes and the smoke clears we see nothing left except a blood splatter on the ground.

Another episode we see fish-like monster attacking a city, killing civilians and some blood is shown. At least twice, we see one of these monsters explode, this is slightly graphic, but avoids being too strong.

Profanity isn't very common; it's usually limited to "damn," "hell," and "bastard." At least one use of "bitch," and two uses of "shit." One kid points his middle finger at Renton. However, the meaning of this isn't quite the same in Japan.

Some fight scenes may be frightening to younger children. Scene with Renton and Holland getting into fights are also potentially upsetting.