It may be a Mint error only in that the coin is an uneven thickness, in which case it would be a planchet error. If the coin is not damaged otherwise (excluding the bubble), though, then it's probably not a provable Mint error. The bubble is probably a lamination problem, which can also be a planchet error. This occurs when the cupro-nickel layer (the "silver" colored layer) separates from the copper middle.
Retail value for the 1984s proof Olympic Coliseum Dollar is $17.00 in PF-67
There is nothing special about a 1984 penny, so its just 1 cent. There are a few 1984 pennies that are referred to as double ear 1984s and from what I have found they are worth about 3,500.00 The ear lobe looks like it has two ear lobes or an extra long one.
The value of a coin depends on many factors, one is the condition, or grade, of the coin. Another factor than can effect the value of the coin is the mint mark on the coin. A 1983 Kennedy Half Dollar has one of three mintmarks - D, S or no mint mark. If the coin has no mint mark on it, it was manufactured in Philadelphia. If it has an S mint mark, it is a proof coin and was minted in San Fransisco. The D mint mark is for the mint in Denver. A 1984 P or D mint mark Kennedy Half in somewhat good, circulated condition is worth about $1. A 1984P in a high mint state condition is worth approximately $120. A 1984D in a high mint state condition is worth about $180. A 1984S can be worth up to $200 in perfect of PF70 condition. Most 25 year old coins that have been in circulation will usually receive a grade of VF20 or so. If this is the case with your coin, its worth about $1.