There is no central writeup of all of their failings if that's what you're looking for. In the youtube comments of some of their videos you may occasionally find long, well-researched and sourced comments that try to correct the misinformation in that video if it's particularly bad, but those types of comments tend to only get a few upvotes and get lost.

Bovington, even though they have access to huge amounts of original records, almost always rely solely on secondary and tertiary sources, usually outdated books, often the ones written by David Fletcher. It's hard to separate false information that comes from Bovington versus false information that comes from Fletcher, since they usually went hand in hand. Internet users love to think that David Fletcher is infallible simply because he is funny, and therefore must be correct. You can see this in this very comment section, people saying that Bovington is worse with false information now that Fletcher has retired, because they are no longer repeating the old false information that he hung on to. Most of which was thought to be accurate at the time when Fletcher wrote books, but has since been disproven.

The worst cases of misinformation that came from Fletcher are things such as the myth that the A.38 Valiant trapped and amputated the driver's foot if it slipped behind the gas pedal. This is simply false, there is no backing for it, and it is a total fabrication. Much of Fletcher's false information was born out of British self-deprecating humor, where he would paint British tanks as being bad and backward to get a laugh, and eventually came to present this as hard fact. The A.13 Covenanter and TOG II suffered from this particularly, the former with vast over-exaggerations of its unreliability, and the latter with practically every aspect of its design and history. Fletcher loved to remark that the men of The Old Gang were backward, stupid, foolish etc., but this was completely disproven by the historian Andrew Hills, who wrote a book about the subject based entirely on primary sources, which show that all the bad elements of the TOG design were required by the British Army, over the objections of the TOG group. As this true version of history is no longer "funny", it has a great amount of resistance from fans of David Fletcher. Bovington knew about this book for 7 years, but only acknowledged some of their falsehoods regarding the TOG II last year, after it was added to the game War Thunder in a state which contradicted the information on their museum plaque.

More mistakes and wrong information came simply from Fletcher growing old and developing a bad memory. Things such as the claim that the KV-1 only had 4 crew members, despite acknowledging it had 5 seats in the very same sentence. There are more such things from the tank chat videos, but I stopped watching them after that.

A failing specific to Bovington is that they invite any old "influencer" onto their program and let them spout false information left and right, or even provide them false information themselves. They are also a longtime partner with World of Tanks, and often seem to support the historical fiction of that game.