The following excerpt is reproduced from Michael A. Gottlieb’s Introduction in Feynman's Tips on Physics: A Supplement to the Feynman Lectures on Physics, by Richard P. Feynman, Michael A. Gottlieb and Ralph Leighton (Addison-Wesley, 2005).
I first heard of Richard Feynman and Ralph Leighton in 1986, through their entertaining book Surely You’re Joking, Mr. Feynman! Thirteen years later I met Ralph at a party. We became friends, and over the next year we worked together on the design of a fantasy stamp honoring Feynman.  All the while Ralph was giving me books to read, by or about Feynman, including (since I am a computer programmer) Feynman Lectures on Computation.  The discussion of quantum mechanical computation in this fascinating book intrigued me, but without having studied quantum mechanics, I had difficulty following the arguments. Ralph recommended I read The Feynman Lectures on Physics Volume III: Quantum Mechanics, which I began, but Chapters 1 and 2 of Volume III are reproduced from Chapters 37 and 38 of Volume I, so I found myself backtracking through references in Volume I rather than progressing through Volume III. I therefore decided to read all The Feynman Lectures from beginning to end—I was determined to learn some quantum mechanics! However, that goal became secondary as time went on and I became increasingly absorbed in Feynman’s fascinating world. The joy of learning physics, simply for the pleasure of it, became my highest priority. I was hooked! About halfway through Volume I, I took a break from programming and spent six months in rural Costa Rica studying The Lectures full-time.
Every afternoon I studied a new lecture and worked on physics problems; in the mornings I reviewed and proofread yesterday’s lecture. I was in e-mail contact with Ralph, and he encouraged me to keep track of errors I mentioned encountering in Volume I. It was not much of a burden, because there were very few errors in that volume. However, as I progressed through Volumes II and III, I was dismayed to discover increasingly more errors. In the end I had compiled a total of more than 170 errors in in The Lectures. Ralph and I were surprised: how could so many errors have been overlooked for so long? We decided to see what could be done about getting them corrected in the next edition.
Then I noticed some intriguing sentences in Feynman’s preface:
"The reason there are no lectures on how to solve problems is because there were recitation sections. Although I did put in three lectures in the first year on how to solve problems, they are not included here. Also there was a lecture on inertial guidance which certainly belongs after the lecture on rotating systems, but which was, unfortunately, omitted."
This suggested the idea of reconstructing the missing lectures and, if they proved interesting, offering them to Caltech and Addison Wesley for inclusion in a more complete and error-corrected edition of The Lectures. But first I had to find the missing lectures, and I was still in Costa Rica! Through a bit of deductive logic and investigation, Ralph was able to locate the lecture notes, which were previously hidden away somewhere between his father’s office and the Caltech Archives. Ralph also obtained tape recordings of the missing lectures, and while researching errata in the Archives after my return to California, I fortuitously discovered the blackboard photos (long believed lost) in a box of miscellaneous negatives. The Feynman heirs generously gave us permission to use these materials, and so, with some useful critiques from Matt Sands, now the only surviving member of the Feynman-Leighton-Sands trio, Ralph and I reconstructed Review B as a sample, and presented it with the errata for The Lectures to Caltech and Addison Wesley.
Addison Wesley received our ideas enthusiastically, but Caltech was initially skeptical. Ralph therefore appealed to Kip Thorne, Richard Feynman Professor of Theoretical Physics at Caltech, who eventually managed to achieve a mutual understanding among all involved, and who generously volunteered his time to oversee our work. Since Caltech did not want to amend the existing volumes of The Lectures for historical reasons, Ralph proposed putting the missing lectures in a separate book. That is the origin of this supplementary volume. It is being published in parallel with a new Definitive Edition of The Feynman Lectures on Physics, in which the errors I found are corrected, as are other errors found by a number of other readers.
Playa Tamarindo, Costa Rica
 Our stamp appears in the liner notes of Back TUVA Future, a CD featuring the Tuvan throat-singing master Ondar and a cameo appearance by Richard Feynman (Warner Bros. 9 47131-2), released in 1999.
 Feynman Lectures on Computation, by Richard P. Feynman, edited by Anthony J. G. Hey and Robin W. Allen, 1996, Addison-Wesley, ISBN 0-201-48991-0.