As far as references to unseen adventures are concerned, things change with the arrival of the Third Doctor. For a start he has had his memory tampered with by the Time Lords - dematerialisation codes, temporal flight equations, etc. He surprises himself when introduced to Liz Shaw by recalling that the people of the planet Delphon communicate with their eyebrows. This doesn't necessarily mean that he has been there, however, but if his eyebrow wiggling really does mean "how do you do?" in that language then it might just suggest he has personal knowledge of the species, who have never featured in the series.
He tells us in The Silurians that he has been potholing before, but not recently, and intimates that he has seen dinosaurs in the flesh. He'll encounter a lot from this incarnation on, but again they haven't been seen on screen before. This story also features the infamous line where the Doctor seems to be suggesting that he is thousands of years old. What he actually says is that his experience covers thousands of years - as in he has witnessed that sort of time span in his travels.
On hearing the alien signals being beamed to and from the aliens in The Ambassadors of Death, he clearly states that he recognises them, but just can't recall the details. He has encountered them before, but the Time Lord-induced amnesia is interfering with that recall. Strange, though, that there doesn't seem to be any trace of recognition when he finally sees their spacecraft and meets the aliens in person.
Another vague memory is of the noise heard when Krakatoa erupted in 1883, as mentioned in Inferno. He may have been there in a multi-Doctor adventure, as we know that the Ninth Doctor was also there at the time of the eruption. He mentions meeting the Queen's grandfather in Paris. That would be George V, who reigned 1910 - 1936. We know he visited France during the First World War, as he suffered a serious accident when he fell from his horse whilst inspecting troops there in 1917.
It should be pointed out that all of these references must relate to his First or Second incarnations as, of course, he is stuck on Earth at this period.
His familiarity with the technology and physical attributes of the Lamadines might just be learned knowledge, but his memory doesn't fail him when it comes to recalling his youth on Gallifrey, and his schooldays with the Master.
That "thousands of years" line makes a comeback in The Mind of Evil, when he is about to claim he has been a scientist for that length of time. This one is harder to square, however, as he really does seem to be suggesting it is his lifespan to date - despite only being around 450 in Tomb of the Cybermen, and travelling uninterrupted with human companions since that story.
This story also has the Doctor telling Jo Grant about the time he was locked in the Tower of London with Sir Walter Raleigh, who would go on about this thing called a potato he had brought back. Raleigh was imprisoned by both Queen Elizabeth and King James, so this is at least his second time spent in the Tower, as he previously told Ian and Barbara that King Henry VIII had sent him there.
The Third Doctor is the first to really name-drop at any opportunity. Saying that he is a personal friend of Chairman Mao might simply have been a way of ingratiating himself with the Chinese peace conference delegate, so doesn't necessarily mean he has met him, let alone count him as a friend.
The Daemons suggests that he has some clouded memory of the titular creatures, the mere mention of Devil's End sending him running off into the night to stop the archaeological dig. Hearing the Master talk of world domination makes him think about Hitler, or possibly Genghis Khan - he can't remember which - suggesting he may have heard both of them speak. Whilst the former could be from a recording, the latter means he must have seen him in person. (He does later claim that the Khan's assembled hordes failed to break into the TARDIS).
Another name-drop is Napoleon Bonaparte in Day of the Daleks. He claims to have given "Boney", as he was entitled to call him, the phrase about an army marching on its stomach. This one does sound a bit more made up for Jo's benefit.
More royal connections: he claims to have attended the coronation of either Queen Elizabeth or Queen Victoria - again he can't recall which.
His claim to be a personal friend of Lord Nelson does sound as if he means it, but his other claims in The Sea Devils to have been at Gallipoli and El Alamein are clearly just attempts to coax someone into lending him their boat. He also mentions the Crimean War, and his Second incarnation had previously said he witnessed the Charge of the Light Brigade, so there may be a kernel of truth hidden in the lie.
In The Time Monster we get more references back to his childhood - schooldays with the Master once again, plus the story he tells Jo of his encounter with the hermit who lived in the mountains above his home. The odd thing about this latter reminiscence is that he says something along the lines of "I laughed too when I heard it" - suggesting it isn't even his own recollection. (It is pinched wholesale from a Buddhist text after all). Was he simply telling Jo an uplifting parable to raise her spirits?
Unless it took place during the potential Season 6b, the banning of Miniscopes occurred before he left Gallifrey. He has visited Metebelis III before, and recognises a Plesiosaur when it attacks the SS Bernice - again suggesting he has seen dinosaurs before. We know that he has claimed to have trained with the Mountain Mauler of Montana, who sounds like a wrestler, but in Carnival of Monsters he also says that he was taught some boxing techniques by John L Sullivan, who was most active in the 1880's. He won 40 of his 44 fights, and only lost one (the other three being two draws and a "no contest"). Sullivan was the last of the great bare knuckle fighters, but the Doctor insists on Queensbury Rules for his fight with Lt Andrews (drawn up by the Marquis of Queensbury - Lord Alfred Douglas' father, and so a key player in the fall of Oscar Wilde).
The Doctor definitely visited the planet of Draconia before - assisting the Fifteenth Emperor in combating a space plague. His story about attending an intergalactic conference and being captured by the Medusoids does sound like another of those made up stories told to cheer Jo up - certainly the description of the other delegates whom he encountered (horses with purple spots etc).
The Doctor finally gets to Metebelis III in The Green Death, and it's not the paradise he has previously described, so he obviously visited a different part of the planet, or he went there at a different point in the planet's history - presumably much later as it seems quite primordial here.
His comments to Sarah about the Vandals having a bad reputation might imply an encounter with them, or it might just be learned knowledge about their culture.
He tells Sarah that he has been to the planet Florana more than once in Death to the Daleks - another good place for a holiday - and also informs her that he has seen a temple in Peru which reminds him of the Exxilon city.
Finally, we get some more name-dropping in Planet of the Spiders - learning some escapology tricks from Harry Houdini (someone he will mention a couple of times in later incarnations, so presumably a real encounter), and he tells Sergeant Benton that some of the best coffee he ever tasted was made by Mrs Pepys. However, in his famous diaries Samuel Pepys states that his wife couldn't stand coffee, much preferring tea. It's possible she might have been good at making it, just never drank it herself. Pepys was also a notorious womaniser, and the lady introduced to the Doctor as his wife might have actually been one of his many mistresses.
The Doctor once again mentions the Gallifreyan hermit story to Sarah, in front of K'anpo (the hermit himself), so this suggests that his story to Jo was a genuine recollection after all.
