- Annoying Video Game Helper: Dr. Kawashima's advice can come off as incredibly condescending, given time.
Dr. Kawashima (said with a disappointed face): “Hmm, a little tired, are we?”
- Scrappy Mechanic: The voice-based tests in both games. It can be very hard for the system to pick up certain words, leading to skewed Brain Ages (and sometimes the game even totally aborts the test if it can't hear you properly). Thankfully, there's an option (meant for use in loud environments) to not allow these tests to show up during Brain Age testing.
- Similarly, any of the minigames that forces you to write under pressure (for example, Word Attack: Space). Brain Age's inability to correctly identify letters becomes extremely frustrating when you're unable to zap that "e"-shaped bullet before it destroys your ship because the game insists what you're writing is an "f." This is especially annoying in "Devilish Calculations" where you must write to correct answer in a few seconds and end up getting the problem wrong because the game failed to recognize the number you wrote.
- The difficulty progression in Devilish Training relies completely upon your performance, rather than skill level or preference. A single good or bad level will automatically increase or decrease the difficulty of the given course, with only an average score keeping you at the same level. Forcing you to Do Well, but Not Perfect, if you want any form of consistency or time to really practice at a certain difficulty.