Yes, mixed metals can corrode each other in a galvanic reaction, but that's not what I'm talking about when I warn you against mixing gallium and or mercury with aluminum. Within seconds, your aluminum will crumble to dust with the mercury. Within minutes, your aluminum will be as fragile as paper with the gallium. It's not mere corrosion, it's near-instant catastrophic destruction. With the mercury, it's obvious. With the gallium, everything will look fine until you poke it with your finger and it falls apart.
The other metal to avoid is tin, if you use active refrigerated cooling. The cold will cause a phase change in the tin, and it will crumble to dust too, right before your eyes. That's something to be aware of when you choose your solder, since most of them contain anything from pure tin to an alloy.
Also be aware that heating and cooling will cause whiskers to form in many metals. Those can cause an explosion in your batteries, or some other unpleasant effect. The size of some lithium batteries in use here is big enough to zip off fingers if they explode while you're gripping your device. Hopefully you're wearing eye protection so you don't need to worry too much about shrapnel.
I always use a face shield in addition to eye protection if I'm doing something that has even a small chance of going badly. It has save my face and my eyes more times than I can count.