Bittersweet Ending: The final two episodes of the anime involve the school going up against the school board for their attempts to cover up a teacher's affair with a student and their cover up of that same student's suicide to prevent the possibility that she was pregnant with the teacher's child from leaking and try to pin an attempted murder charge on Anko (I think) for stabbing the teacher when it is confirmed that, after hearing about his student love's suicide, the teacher tried to commit suicide as well. While the school faces being shut down as they refuse to turn over Onizuka for an (obviously fake) assault charge and Anko, Onizuka steps in and gets the media involved to cause a storm around the events to expose the school board's cover up. Then Onizuka takes the blame for the attempted murder despite his students having evidence that it was an attempted suicide and Anko finally coming around and trying to rescue him. Onizuka is nearly taken into custody but, as per the norm, he manages to escape as the teacher wakes up from his injuries. It's all but confirmed that the School Board will be unable to deny the charges of covering up the suicide and suicide attempt and all the students in class 3-4 are able to trust teachers. Onizuka goes on the run and ends up in The United States of America at a California Junior High in charge of a class full of delinquents. Sadly it's implied that Onizuka will be unable to return to Japan after this despite his role in exposing the coverup and his student and Aizawa will never see him again.
Cargo Ship: At times the only thing that seems to prevent Uchiyamada from marrying his Cresta is the unfortunate fact that it's kinda sorta... unconventional.
If violence doesn't do the trick, more violence will. It's perfectly okay to put your colleagues' and students' life in danger when you're a teacher if there is a moral lesson behind the action. Also, some examples of Onizuka "resolving" problems of his students fall into this.
Be Yourself, Tokiwa. When you've been gang-raped, lost your trust in the men and humanity as a whole, when you feel insecure and seen mainly as a sexual object by the opposite sex... remember that you're a girl. You can always cry. Admittedly, her own "solution" included antagonizing and beating up random men which almost made her gang-raped the second time, but still, Onizuka's response is along the lines of "you are a girl, you are weak, you are always going to be a victim, roll with it" and he does nothing to, say, bring punishment to the guys who raped her in the first place.
Fan-Preferred Couple: Onizuka and Urumi, at least as far as the majority of the Western fanbase first introduced to the series through GTO is concerned. The pairing tends to get more support due to the opinion that Urumi has more of a developed personality, while Fuyutsuki too obviously fills in the role of obligatory love interest.
Ayame and returning Love Interest Shinomi from Shonan 14 days join the fray.
Think about the last middle schooler you saw. Now picture them pregnant, living alone, and holding a job. How exactly would a disowned 13 year old rent an apartment without a credit history, raise a child by herself, and in the most expensive city in the world, all with no outside help or child services intervention? Either Japan has the world's greatest and most beneficial welfare system, she had the world's nicest landlord, or the writers are greatly exaggerating for dramatic purposes.
Kick the Son of a Bitch: The teacher Miyabi framed. Even after the reveal that she made up everything about being abused by him because he had a fiancee and she felt betrayed, Onizuka revels that he was, in fact, messing around with her.
To be fair, the teacher's fault was not heading Miyabi off even after he came to realize that she had developed a serious crush on him. Did he deserve punishment for this? Sure. Did he deserve to be framed as a child rapist, to have his entire teaching career ruined, to lose his fiancee and to get severely beaten up(twice) as a result of this? Probably not. This whole incident makes it hard to feel sorry for Miyabi.
See Urumi's Magnificent Bastardry. After her setting up three classmates (no matter how huge bitches they were) to be gang-raped by several old perverts with strange fetishes, it's hard to view her as a positive character. To a reader. In-universe she doesn't even get called out for this.
Shonan's mayor from 14 Days. His debut moment? Making a policy that takes children from shelters such as White Swan, unwanted and[/or abandoned children, mind you, and taking them back to their parents who either don't want them, as is the case with Miko and Riko, or abusive monsters like Sakurako's father described above. His reason for doing this? To rack up votes from housewives.
Also from 14 Days, Seiya's mother abandoned him for her Bastard Boyfriend who threatened to hit her if she didn't stop Seiya from hitting him and pinned the blame on her for Seiya trying to kill him over his abuse and did nothing to help her flesh and blood from being beat up by said boyfriend in front of her. Riko and Miko's mother kept trying to get rid of them and committed suicide in the end because she didn't want to have the responsiblity to look after them and their father didn't want the responsibility either, and thenthere's Sakurako's father. It all but makes Onizuka's message at the end of the Seiya arc the more powerful.
Nightmare Fuel: Onizuka is mistakenly forced into a marriage with a Kuchisake-Onna; her family share the same trait of a Stepford Smiler with saw teeth. Onizuka also encounters one in Okinawa, though it was a young girl and actually quite nice.
Many people may not realize that GTO was an almost direct sequel to a lesser-known manga series, Shonan Junai Gumi. They most likely assumed that GTO started in media res, though it could just be the fault of TokyoPop for Americans.
Shonan Junai Gumi was marketed as GTO: The Early Years in North America and UK, but it was marketed as Young GTO in France.
Tear Jerker: While Onizuka is dying of his Game-Breaking Injury, his old Nakama Ryuji refuses to believe that Onizuka could be hurt in any way and says that he can not die. When Onizuka's heart stops beating, he punches him in the chest hoping to wake him up, crying.
In the live-action drama episode 11, Onizuka was being forced apart from his students. As he was being dragged away, he tells each of his students something relating to their interests (showing just how well he got to know them) or a final piece of advice.