Yeah, completely agree with this.

It looks like it's set prior to the finale.

I'm not so sure about that. I'd guess it is still set after the finale but the Rider fighting against random Roidmudes is all done in flashbacks. The setting itself is after the finale; Shinnosuke finds the Newton Eyecon and investigates the re-appearance of the three Roidmudes and meets Ghost.

Because if the crossover would be set before the finale, Shinnosuke would've recognized Ghost in his dream/hallucination/trip to Helheim.

How come the traffic police officer didn't recognize his face in the news at the times Chase was shown on tv? Especially on ep 26?

After seeing Mach use Chaser's signal bike for a fusion form, I was thinking, can Chaser do that with Mach? Or can Chaser use Deadheat and create a triple rider fusion or Deadheat Mach using Chaser?

I dont think so. Banno said the Mach System wasnt even supposed to be able to aquire such a form.

Rinna Build the Chaser System based on the Mach system so unless she made Chaser compatible with Machs Signal Bikes I dont think this would be possible.

I thought Chase's belt was just a copy of the Mach Driver Rinna made to experiment on, and Kiriko gave it to Chase. Perhaps I'm remembering this wrong.

It was. But the Signal Chaser and Signal Ax were still developed at a later time. So she had to modify the Mach Driver to work with the Signal Chaser.

Has anyone ever had a rouzing game of poker using the Blade cards?

1) Why didn't they create a new suit for Mach after syncing the Chaser signal bike? It would've looked like a Mach version of Mashin Chaser.

2) Drive felt like 555 to me... will Ghost feel like Blade?