LorgSkyegon

Question: When Zeus is on the phone with Simon in the subway, Zeus says that McClane was on his way. Simon responds that they weren't playing by the rules, hangs up and a few moments later the bomb goes off. McClane states that Simon wanted the subway bomb to go off. Why would McClane think it was Simon's intention to have the bomb go off whether they both show up or not?

Answer: Because Simon basically gave them an impossible task. Given NYC traffic, getting 90 blocks in 30 minutes is a Sisyphean task.

LorgSkyegon

Answer: Because when McClane found the bomb, supposedly before Simon's deadline, the binary liquid began to mix, indicating it was about to go off.

Bishop73