Cloaked
We see Iago in the opening scenes cloaked, his head covered as he follows Othello and Desdemona unseen by them. This is a symbol of his deception as he is setting out to destroy Othello.
Desdemona
We clearly see Desdemona standing in front of a wall covered with the shadows of war banners flying in the wind from Othello's point of view. This imagery shows us that Desdemona's love is real with Othello, not some shadow as Iago will soon convince Othello to believe.
Stopped
We watch as Roderigo carries on walking as Iago has stopped. Roderigo quickly returns to him, and this is a symbol that Iago has Roderigo on a string just as he wants, in order to see his plan of betrayal come to fruition.
Another Cup
Iago feeds Cassio strong drink, which he does not normally partake in. The drinks which he consumes becomes a symbol of Iago poisoning Cassio in order to take control of him as a pawn in his plan to tear down Othello.
Scarf
Othello is seen stepping on Desdemona's scarf. This is a symbol that he believes Iago's lies that she is sleeping with Cassio.