Other mistake: When Spike is thrown out of the base by Megatron at the end of the episode, Optimus calls him 'Splik'.
Desertion of the Dinobots (1) - S2-E19
Plot hole: Perceptor discovers that the reason for their malfunctioning is because their Cybertonium has deteriorated after millions of years of being exposed to Earth's atmosphere. The key word here being 'millions'. This explains why the original Transformers who crash landed on Earth (4 million years ago) are affected, but newer characters like Perceptor, Powerglide, Hoist, etc. are affected despite the fact that they have only been on Earth recently.
Plot hole: Omega Supreme transforms his arm into a rocket and blasts off to the moon, but later, he transforms fully, but he left his body on earth, how was he able to transform?
Other mistake: When the Decepticons shoot the monument at the end, Optimus runs to save it, you can see two Optimuses (Most likely because the animators forgot to get rid of the other prime which is just standing there).
Continuity mistake: At the beginning when Soundwave is attacking the bunker as he ejects his cassettes he says Buzzsaw (the gold condor) but instead ejects Laserbeak (the red condor).
Continuity mistake: Red Alert's door abbreviation has always been an F, then a shield, then a D, but when he is racing through the city when the Autobots are looking for him, he passes them and the abbreviation is: E, shield, D.
Audio problem: At the end, Inferno comes out from the blaze with Red Alert in his arms, Red Alert then says something, but his mouth doesn't match what he says.
Answer: This was actually one of many errors in Transformers, the Constructicons MUST have been built on Cybertron, the only transformers genuinely built on earth were the dinobots, reason being Vector Sigma has to give personalities to each and every robot, else they end up like the dinobots, very simple and dumb. For reference watch the episode "The Key to Vector Sigma" which introduces the Stunticons and Arielbots - both Megatron and Optimus Prime have to go to Vector Sigma to get decent personality traits installed, prior to this the new robots are controlled by remote controllers and have no AI.