The Ramsey number survey by Radziszowski (Small Ramsey Numbers, revision 16 ) has a couple of footnotes mentioning incorrect values. Unfortunately there is not much information on the cause of or correction of such errors.

On page 6:

(h)
The claim that $R(5, 5) = 50$ posted on the web [Stone] is in error, and despite being shown to be incorrect more than once, this value is still being cited by some authors. The bound $R(3, 13) ≥ 60$ [XieZ] cited in the 1995 version of this survey was shown to be incorrect in [Piw1]. Another incorrect construction for $R(3, 10) ≥ 41$ was described in [DuHu].

On page 25, in the "Cycles versus books" section:

(b)
$R(C_{4},B_{12}) = 21$ [Tse1], $R(C_{4},B_{13}) = 22$, $R(C_{4},B_{14}) = 24$ [Tse2].
$R(C_{4},B_{8}) = 17$ [Tse2] (it was reported incorrectly in [FRS7] to be 16)

The [Piw1] reference is:

Piwakowski, Applying Tabu Search to Determine New Ramsey Graphs, Electronic Journal of Combinatorics, http://www.combinatorics.org, #R6, 3(1) (1996), 4 pages.

This paper says (note: [11] in this paper is [XieZ] mentioned by Radziszowski):

Finally, let us note that a better lower bound $R(3,13) ≥ 60$ was claimed in [11]. Unfortunately, the cyclic graph $C_{59}(1,3,5,7,16,25)$ described in that paper as a $(3,13;59)$-Rg contains a number of indepdendent sets of size 13, for example $\{0,2,6,10,14,20,24,28,32,38,42,46,50\}$.