In "Obligatory Boo Meme", Tails Doll, unlike the Metals, shows no reaction to the "BOO" sign. This may be due to the doll's Memetic Psychopath status.
In "Dancing Banana", Metallix states he, Metal Sonic, and Mecha Sonic Mk. II need 20 ounces worth of dancingbananas to create a geyser in Hydrocity Zone. Metallix is from Super Mario Bros. Z, a Web Animation created by a British man. And his name comes from a British comic. So it makes sense why he'd use the imperial system rather than the metric system.
In "Eggman Needs Sonic Dead", Metallix rants on the inefficiency of Eggman's plans to defeat Sonic. (In case you ask, because of a large chain of laziness, Eggman sends Metal Sonic, who sends Mecha Sonic Mk. II, who sends Prototype, who sends Phil, who sends Motobugs. And Mecha Mk. II apparently has a bone to pick with Prototype, since when the two have Sonic cornered, Mecha, instead of killing Sonic, goes out of the way to assassinate Prototype. Who Mecha hired to kill Sonic.) Of course he would make such a rant.
Neo Metal Sonic being French. As a commenter pointed out, it's because of his ability to disguise himself as other individuals, an ability that Team Fortress 2's Spy also has. And Spy is French.
Some people think that Mecha Sonic Mk. II's relationship with Jenny Wakeman is squicky, as Jenny is a teenage robot, and Mecha, based on his voice and build, is significantly older. Thing is, they're wrong about Mecha; he was modeled after a fifteen year old, making him a teenager. Just like Jenny.
The Metals being able to recognize Sonic when he tries to put on a false identity is more than just them being smarter than the Super Special Sonic Search and Smash Squad. Given how the series' main premise is that all Sonic robots live under the same roof, they had to learn to tell each other apart from both each other and Sonic. Now, the main difference between Sonic and the Metals is that Sonic's eyes are green with white sclerae, while the Metals' eyes are red, either with black sclerae or, in the case of Prototype and Mecha Sonic Mk.II, without sclerae. The only robots that don't fit this pattern are Pseudo Sonic, who had his role of "Sonic robot who lives on an island filled with abandoned badniks" taken from him and given to Mk.II and, as such, likely has a bad relationship with the Metals, and Shard, who had a Heel–Face Turn and, as such, is probably enemies with the Metals as well (except probably Mk.II, who also had a Heel–Face Turn in another comic). (And before you bring out scenes where Shard's eyes do fit that pattern, that's when he's in "battle mode"; normally, they're green with black sclerae.)
