I would go for discordances in the tree of life, there are many examples of alleged “convergent evolution” where 2 organisms share a similar trait (similar even at a genetic level)
Why would that indicate ID?
One example would be the sonar in dolphins and bats, both organisms have a similar sonar system (same genes) the similarities are not just trivial,. Both organisms share the same genetic material.
And why would that similarity indicate ID?
For a mechanism like random mutations + natural selection this is very hard to explain because this would imply that 2 independent organisms suffered from the exact same mutations hundreds of times.
No, it doesn't, because that's not how evolution works.
Firstly, your language here needs fixing. They didn't "suffer" mutations. Mutations arise naturally and are not always detrimental, so to say that they are "suffered" seems to be misleading language.
Secondly, they don't have to have "the same mutations hundreds of times". They are already different forms with different DNA arrangements, and the forms that can result from these arrangements may produce similar traits.
For starters, your comparison of the two fails because both sonar in bats and dolphins function entirely differently - they don't use the exact same biological mechanism. Bats emit sound-waves from their mouths and noses which bounce back and hit their ears. Dolphins emit clicks from their forehead which travel back and hit fat-filled cavities in their jaws. The two processes are completely different, they just happen to have similar functions.
This isn't indication of anything other than the fact that a particular function may be beneficial to two separate organisms in two separate environments, and the fact that both evolved entirely differently to each other means that they do not require "the same mutations". Clearly, they were completely different mutations giving rise to completely different forms that simply happened to have a similar (although, functionally quite different) traits.
This mechanism would predict “similar” paths at a superfitial level like in the wings of bats and birds. But not identical paths. (this is like finding a mammals with feathers wich is something that evolutionists always quote as an example of something that would falsify their theory)
How is that any different to what evolution predicts? What could be found that would falsify ID?
From the point of view of ID this is very easy to explain, intelligent designers are not worried about statistical improbability.
It's also very easy to explain if you believe a wizard did it with magic.
Just to be clear the example of bats and dolphins is one of many similar examples, and new examples are constantly being discovered. This was not expected by darwinists.
And none of it indicates anything about ID whatsoever.