Watch measures seemingly impossible heart rate on indoor cycling. How is this possible.

I have recently gotten into a cardio machine called an Airdyne. Which is essentially a fan bike with arm pedals.

Every day this week I have gone for max calories burned in 5 minutes. I recorded the exercise using the "indoor cycling" exercise on my watch. Every day I tried to put in maximum effort but since this is a new exercise that tends to change daily. On day 3 I did wear the watch on my right wrist.

What is odd to me:

In every case the watch and the machine disagree significantly. And in the case of day 3 I believe my watch gave me an impossible heart rate measurement. No way I was sustaining an 184 average... like I felt maybe more tired on this one than others but not that much.

I guess this really makes me question the accuracy of my watch. Is this possibly accurate? Especially day 3? Why did my watch record them so differently? How can you explain the delayed jump of heart rate on the third.

Here are the graphs:

Day 1

Day 2

Day 3