Research has shown that your brain registers the same impulses whether you mentally go through actions in your mind or actually do them with your body. So it goes without saying that you can learn the tai chi form you’re working on by going through it in your mind.
The classic Taijiquan Lun says the the whole body should move if any part moves. This is the “whole body moves as a single unit” that is so often referred to. If you practice this completely you would make sure you integrate your mind, or the brain’s mental processes, into the activity of moving as a single unit. So, it makes sense to practice using the mind to learn and recall tai chi form or any other activities associated with tai chi.
Using the visualization mnemonic to learn is something makes tai chi an excellent practice for helping to improve other areas of life.
You can find many websites providing tips and other information on improving your memory skills.
Another helpful tool is to play music while you do the form. Many tai chi practitioners do play slow music while they do form, such as Chinese guzheng instrumental music or non-percussion flute music.
Many practitioners spend a lot of time and effort remembering the names of moves and postures, but I have not done that. Other than to remember main postures, such as single whip or wuqi and so on, at least at first, early practitioners get caught up in remembering the names of moves rather than the moves themselves. That is a major distraction. I recommend learning the moves first, then worry about the names later when you are very comfortable with recall.
One more tip: if the thought arises then that moment is the time to practice tai chi. I often ask learners what they have practiced since the last time we practiced together. And often they say sheepishly, “Well, not much.” I get nothing at all regularly. Then I ask, “Did you think of tai chi at all during the week?” and often the answer is yes. Then I say, “That is the time you should practice, because it is the spirit talking and reaching out and giving you a chance. Don’t pass it up next time you hear it speaking.”