Exceptional memory

My 2.5 year old has an incredible memory. He is cognitively delayed and has a speech delay. We are awaiting an evaluation for autism and ADHD (lots of reasons for us thinking these two).

We like to watch the same shows/movies but we definitely rotate through a lot of different ones. My son does not say 2 words combined and maybe has about 100 word vocabulary. However, when we are watching something he will repeat a phrase before the characters say it. He will mimic actions or dance moves right before it happens. Again, we don't watch these things on repeat, but he's seen them a handful of times.

He has also memorized routes we take on the road. If we go a different way than normal or we don't turn on a road to Grandma's house and just pass by it, he throws a tantrum.

Anyone else have toddlers like this? How can I use this to maximize his learning??