《忍者龜2》在任天堂紅白機(FAMICOM/NES)上的密技：

關卡選擇：對於日本版本：當標題畫面出現時，輸入左鍵三次、B鍵三次、A鍵三次，然後按開始。需要在很短的時間內操作完成。對於美國版本（NES）：當標題畫面出現時，依序輸入下鍵五次、右鍵七次，然後按B、A和開始鍵。

十條命：當標題畫面出現時，輸入右鍵三次、B鍵三次、A鍵三次，然後按開始鍵即可。這是日本版本的操作。對於美國版本：當看到標題畫面時，輸入上鍵、右鍵兩次、下鍵三次、左鍵四次，然後按BA和開始鍵。

美版的額外生命與舞台選擇：在標題畫面上按下 B、A、B、A、上、下、B、A、左、右、B、A、開始。

美版的額外生命增加：在標題畫面上，按上、右、右、下、下、下、左、左、左、左、B、A、開始。

與最終頭目許瑞德的對決技巧：在最後的決鬥中，許瑞德會有分身，兩者外觀完全一樣，雖然其中一位是假的，但都會使用閃電攻擊，將玩家變成烏龜。當任何一位許瑞德即將被打敗時，頭盔會飛走，此時不要攻擊，因為這個是分身，只要沒有頭盔就無法使用閃電攻擊。這時候可以忽略分身，專心攻擊真身即可。注意如果先把分身消滅掉，很快就會出現另一位分身，這時候又需要應付兩個閃電攻擊。

累積積分的地方：在下水道中與貝克博士(Baxter Stockman)的第一次戰鬥中，他會飛來飛去並丟下會攻擊玩家的捕鼠器，而不是直接攻擊玩家。在擊敗它們後，他會掉落更多的老鼠，而且會無限的持續。可以反覆攻擊他掉落的老鼠夾並累積分數，直到生命增加。

還有一個地方可以無限刷分，而且比下水道安全。在高速公路階段，有騎摩托車的大腳兵。當到達位於螢幕頂部的第一個大灰色輪胎時，只要不進一步移動螢幕，這些大腳兵就會無限產生。所要做的就是站在那裡，等待騎自行車的大腳兵出現，殺死他（使用 A+B 攻擊），然後重複操作直到獲得額外的生命。

The cheat codes for "Teenage Mutant Ninja Turtles 2" on the Famicom /Nintendo Entertainment System:

Level selection: For the Japanese version: When the title screen appears, input the left button three times, the B button three times, the A button three times, and then press Start. This needs to be done within a short period. For the American version (NES): When the title screen appears, input the down button five times, the right button seven times, and then press the B, A, and Start buttons.

Ten lives: When the title screen appears, input the right button three times, the B button three times, the A button three times, and then press the Start button. This is for the Japanese version. For the American version: When you see the title screen, input the up button, the right button twice, the down button three times, the left button four times, and then press the BA and Start buttons.

Extra lives and stage selection in the American version: On the title screen, press B, A, B, A, Up, Down, B, A, Left, Right, B, A, Start.

Increase in extra lives for the American version: On the title screen, press Up, Right, Right, Down, Down, Down, Left, Left, Left, Left, B, A, Start.

Tips for the final boss, Shredder: During the final duel, Shredder will have clones, both identical in appearance. Although one is fake, they both use lightning attacks that turn the player into a turtle. When any Shredder clone is about to be defeated, the helmet will fly off. At this point, refrain from attacking because this is the clone. Without the helmet, they cannot use lightning attacks. Ignore the clone and focus on attacking the real Shredder. Note that if you defeat a clone first, another one will quickly appear, requiring you to deal with two lightning attacks again.

Places to accumulate points: During the first battle with Baxter Stockman in the sewers, he will fly around and drop mousetraps that attack the player instead of directly attacking. After defeating them, he will drop more mousetraps indefinitely. You can repeatedly attack the mousetraps he drops to accumulate points until your lives increase. There is another place to accumulate points infinitely, and it's safer than the sewers. During the highway stage, there are Foot Soldiers riding motorcycles. When you reach the first large gray tire at the top of the screen, as long as you don't move the screen further, these Foot Soldiers will spawn infinitely. Stand there, wait for a Foot Soldier on a bike to appear, kill him (use the A+B attack), and then repeat the process until you get extra lives.