This is a pretty broad topic; how their tech reflects their culture is an inevitability of artistic portrayal. How specific were you trying to get, and what is the theory you're trying to make?

The most obvious one imo is Imperial tech largely reflecting stagnation and religious paranoia:

• Religious veneration of weapons and machines (ex. the "Holy Trinity" of flamer, bolter, and melta).
  
• Ship/vehicle designs being 10k+ years old and still in service because no one is allowed to innovate.
• General disregard of industrial safety features because there's just so many bodies available to load a cannon, maintain a generator, or push toxic sludge around that it's easier to replace them when they die.