Galatasaray are to be sanctioned after their fans threw flares onto the Emirates pitch at Wednesday, but their supporters also caused destruction in the stands.
According to Twitter user Bearupatree, who works at Arsenal's home, more than 100 seats in the away end were broken.
He also says that the Turkish supporters left two rows of seats "collapsed" and 2,800 seats loose; the cost of the damage is not yet known.
The Independent have contacted Arsenal about the cost of the damage.
The Gunners could be fined by Uefa following crowd disturbances during the match, with the Turkish club likely to face much more severe sanctions after their supporters threw flares.
The governing body on Thursday confirmed disciplinary proceedings had been opened against four teams - Arsenal, Galatasaray, Basle and Borussia Dortmund - in the wake of incidents during Wednesday night's European ties.
At the Emirates Stadium, several flares were thrown onto the pitch from the section where the 3,000-strong travelling Galatasaray supporters were located towards the end of the first half, causing the Group D match to be briefly halted.
Metropolitan Police confirmed there had been six arrests as part of their operation for the European tie in north London, two of which were for entering the ground with flares.
Uefa view it as the home side's responsibility to search supporters for any illegal items before they come into the stadium.
There were disturbances before the match, when Galatasaray fans had let off flares in streets around Finsbury Park and thrown some into the Tollington Arms pub.
Additional reporting by PAReuse content