Compiled list:
Canon mistakes in ME: Deception- Gillian's autism - now she, by her own words, grew up from it, which is impossible
- Quarian's names - titling kvarian Fothar vas Maynar (and others) like Maynar means, you adressed them by name of their ship, not by their own name.
- Gas suckers - quarians breathing air, their masks only looks like gas mask, their function is filtration of air
- Claiming that Hendel never visit Omega before - Hendel was on Omega in Ascension whole three chapters
- Hendel can't know that Anderson and Kahlee are together and on the Citadel - they got together after Hendel leaving with quarians and Kahlee had no contact with them (dialog between her and Grayson in Retribution and fact, that Gillian don't know about father's death)
- Friendship of Gillian and Nick - there was only one and last contact between them in Ascension. Nick overthrow her milk and she went mad and nearly kill him
- Gillian knowing about her adoption - nothing suggest this in Ascension, in fact Grayson had strict order from TIM pretending, he is her real father
- Gillian claiming that child in Academy tormented her - nothing suggesting that, in fact they only ignoring her, incident with Nick was unique
- Tantalus drive core on batarian ship - Tantalus core was high secret experiental drive core using only on Normandy, batarians can't have it
- Aria T'Loak's biotic - Aria is very strong biotic, but in Deception she need her bodyguards to put barrier on her
11.
The Citadel is described being star shaped - Citadel is actually like a hollow cylinder.
12.
There is Batarian embassy in the Citedel - Batarians closed their embassy in after the Citadel Council sided with humans regarding border dispute.
13.
Some characters visit Chora's Den - Chora's Den was closed after events of ME1.
14.
Citadel surrounded by stars - Citadel is in the middle of nebula with only one star, Widow, visible.
15.
Krogan dies when Kai Leng severes stabs knife in his neck and severes spine - Krogan biology doesn't work that way.
16.
Biotics are told to have different levels in their Biotic abilities - There is no such thing, there are only different types of implants.
17.
Hendel Mitra is described as heterosexual - Hendel is homosexual.
18.
Deception claims Asari found The Citadel first and learned to use mass effect technology after that - How did they got in the Citadel at the first without using mass effect?
19.
Deception tells that The Citadel is a Reaper trap that Reapers used successufully during the events of ME1 - That never happended due Prothean scientists reprogamming the Keepers
and Shepard foiling Sovereigns plan to manuallu override Citadel relay
function.
21.
Asari are told to be asexual - In ME1 Liara describes Asari as mono-gender, all female species.
22.
Quarian's names, continued - none of the quarians named in Deception have a clan-name (examples: Tali'
Zorah, Han'
Gerrel, Daro'
Xen, Shala'
Raan, etc.
23.
Asari Council member saying "My God" - Asari don't believe in any form of male God, their religion is a monotheistic one based on the Goddess Athame.
24.
Kai Leng visits an auction house on the Batarian homeworld Kar'Shan - the Batarian homeworld is closed off to outside races, especially humans.
25.
Batarian pirates raid slaves from the Turian homeworld of Pavalen - yeah, a bunch of no-name pirates managed to raid supplies and slaves from the homeworld of one of the strongest and most militaristic of races in the Mass Effect universe.
26.
Public is allowed in the Citadel Council chamber - In ME1 only very few people have a privilegde to meet them.
27.
Characters Gillian and Nick are 18 years old in Deception - These characters were 12 - 13 years old in previous novels set 2 years before Deception
28.
Hand Weapons that fire at "relativistic speeds" - for those who doesn't know it the term relativistic speed means close or apprising the speed of light, the term is usually used about speed higher than 80% of C - considering that a sand corn fired of those speeds will have the impact of 90 kg TNT and also that a main gun on a Everest class dreadnought only fires at 1.3% of C i would say that relativistic speeds might be a bit high.
29.
TIM's hideout - in Retribution is written, that TIM is hidding on space station, which changing location after every visitor including Leng. Now TIM is on the planet and staying there after Leng's visit.
30.
Gillian's visit in Afterlife - Afterlife is most popular bar on Omega and people waiting hours to get in (Retribution). Now Gillian enter it immediately and bouncer don't stop her.
31.
Quarian's clothing - Quarians wear enviromentally-sealed 'enviro-suits' to protect their weakened immune systems... they do not wear "a motley collection of clothing, held together by a variety of straps and metal fasteners".