Retcons

A Retcon (Retroactive continuity adjustment) is the alteration of previously established facts within the continuity of a fictional work.

EGS is pretty good in this regard, with lot of things obviously planed much sooner than when they appeared. Still, there ARE some cases where Dan decided that it's better to break continuity, and there are others where he thinks about it. One remarkable point is that he is not trying to hide those cases from the readers: in fact, he points them out.

Actual Comic Changes

The Power of Pheromones

Dan's original notion of pheromones the FV5 will have was little too optimistic, as mentioned in commentary of EGS Main Story Comic for 2002-06-14. He later decided that they are not powerful enough to overcame Sarah's heterosexuality and EGS Main Story Comic for 2002-06-30 was changed so Sarah and Elliot did NOT actually kissed. Original version is still linked from commentary.

It also wasn't powerful enough to overcame Susan's ... well to make Susan behave out of character at EGS Main Story Comic for 2002-06-27 and call Elliot "cutie" and "honey". Although this may also be related to overall deepening of Susan's character. Again, original version is still linked from commentary.

Canonicity Changes

Matt and Rat

There are not supposed to be any fourth-wall breaking stuff in Main Universe except the introductory story line. Well ... there is. Specifically, Dan originally put Matt and Rat, his characters from earlier comic, into the Main Universe. He did not (yet) actually changed the comics itself, but refused to acknowledge it being canon in commentary and later pretended panels with them don't exists.

Temporary Changes

For several hours (judging by timestamp in filename, between Fri, 11 Mar 2016 20:29:02 GMT and Sat, 12 Mar 2016 02:51:39 GMT) the comics on EGS Main Story Comic for 2013-01-21 lost last three panels. The commentary still referred to missing panels, so it didn't seemed like deliberate change. Because Dan referenced the gauntlet on that day's NP, SeriousJupiter noticed the same day. (current (fixed) image, shorter image, original image.) Dan's reaction on being told about the missing panels was "Oh carp. It’s because I’m a dummy and tried to remove an outdated update schedule message and didn’t upload the double-sized version. Fixing ASAP, thanks for telling me." (mentioned in same thread by Scotty).

Non-continuity so can be just said to be retconned changed

Called speed record for retconning, EGS:NP Comic for 2017-07-19 was published and just few hours afterwards declared to contain obvious continuity issue and therefore be retconned out and replaced with EGS:NP Comic for 2017-07-21 with different explanation.

Ideas/Backstory Changes

Elliot's Inner Demons

Originally, Elliot had a lot of pent up rage that could be unleashed though a special move, making him significantly more powerful, but kinda crazy and out of control. These "inner demons" were mentioned in 2002, but later explained out. Then Dan forgot he already explained it and after getting the question again he again answered it.

Melissa

When Melissa first appeared, she and Justin had simply gone out on one date and she'd become obsessed. Later, Justin's story evolved and with it also Melisa's role (also, Noah appeared). The whole backstory was then hinted about mentioning that it's retcon and finally fully explained in EGS Main Story Comic for 2011-01-31.

Ellen's Depressions

Ellen had a pretty unhealthy lifestyle before starting school ... but it IS possible she was originally supposed to have depressions but Dan dropped it due to it being tone shift (see comment on that page).

The Skull Haunting Grace

Grace was haunted by skull around the Painted Black. In commentary, Dan admitted he doesn't remember what was that supposed to represent in the original vague plan.

When the skull appears for the last time, it changes into creature Grace can hug, later confirmed to be Lespuko.

It might've been Grace's Lespuko parent, or maybe her Lespuko side she merged with (her form changed when the creature disappeared).

Painted Black Changes

Painted Black was the first story EGS was supposed to have: everything before that was setting up for it. Dan provides whole storyline about how it changed from original ideas to how it looks. He doesn't add exact timeline, but it is possible that some changes were finished with comics already running; the secrecy of everything could've masked a lot.

For example, the explanation provided in Shade, part 2 was later referred to as "version of the story for people not in "the need to know"", but might've been actually change.

Magus intervention in Sister

The Sister story arc originally involved TF Gun breaking, Tedd zapping Elliot just because being angry, Grace coming up with wall-of-text plan and disturbingly convenient location of Dewitchery Diamond in ridiculously low-security facility.

Tedd later noted how weird the TF Gun breaking was and Magus was retconned to follow Pandoras plan of the whole thing, breaking the gun, influencing lot of people to follow that ridiculous plan and with Sirleck, bribing the guard which presumably would explain how the diamond got on display.

To repeat the timeframe: 2002, Sister ; 2005, Magus appears and is retconned into having role in Sister ; 2010, first direct mention of that role ; 2017, almost full explanation.

FV5

On EGS Main Story Comic for 2015-06-08 Dan mentioned that he overdid the FV5 Ellen on EGS Main Story Comic for 2008-04-11 and since then is using the same effects in sketchbook, but that it's not consistent with how FV5 is supposed to function.

This is not completely clear, but it likely means he will start drawing FV5 Ellen with smaller boobs. Dan being Dan, he talks about it instead of leaving it be and hoping people will blame it on art change.

Hammers

When Dr. Germahn explained the Hammers for first time on EGS Main Story Comic for 2002-03-13, he mentioned that they can't be used if the situation is serious. Obviously, the situation Susan and Nanase were in in France WAS serious, so it seems like retcon that they could use them. Note that it can be argued that the mugger didn't do anything offensive, but the explanation was definitely retconed.

Carol

Carol originally wasn't supposed to be Sarah's sister. That's the REAL reason behind Elliot not recognizing her at EGS Main Story Comic for 2010-11-05, as explained in that comic's commentary.

Liz Gets Magic

Liz seems to get magic based on EGS:NP Comic for 2016-08-26 ... despite the fact that there was nothing about her having magic in earlier comics which happened after this one. On the other hand, Liz isn't featured on-panel enough for this to be problem ... probably ...

PTTAOLUTASF

PTTAOLUTASF was possibly retconned twice - unless the first "retcon" was planned from start. When it first appeared, it was just jokingly underfunded and low security. The commentary from October 20, 2014 still talks about it, however the comics from 2010 mentions that Sirleck bribed the guard (without specifying what was the bribe for).

The second retcon is that the facility is actually trap. It's not SUPPOSED to prevent people from getting in - it's supposed to catch them when leaving with some artefacts - and it deliberately looks even less guarded than it is.