Simultaneity

light[t_, p_, s_] := p + t {s, 1};
eye = Import[
   "http://a2.twimg.com/profile_images/1124979238/Eye_RGB__1__\
reasonably_small.jpg"];
spark = Import["http://cdn3.staztic.com/logos/spark-10.png"];
frame[t_] :=
  Show[
   Graphics[{
     Line[{{0, t}, {2, t}}],
     PointSize[Medium],
     Point[{{0, t}, {2, t}}],
     Red, Rectangle[{0.9, t - 0.1}, {1.1, t + 0.1}],
     Inset[eye, {4, t}, {Right, Center}, 0.5],
     Green,
     If[Abs[t - 2.5] < 0.1,
      Disk[{3.5, 2.5}, 0.1],
      Opacity[1]
      ],
     If[Abs[t - 4.5] < 0.1,
      Disk[{3.5, 4.5}, 0.1],
      Opacity[1]
      ],
     If[Abs[t - 1] < 0.1,
      {Inset[spark, {0, 1}, {Center, Center}, 0.5],
       Inset[spark, {2, 1}, {Center, Center}, 0.5]},
      Opacity[1]
      ]
     }, PlotRange -> {{-1, 4}, {-0.1, 6.1}}],
   ParametricPlot[{light[Min[T, 1], {1, 0}, 1],
     light[Min[T, 1], {1, 0}, -1]}, {T, -10^-3, t},
    PlotStyle -> Directive[Thick, Darker@Yellow]],
   If[t > 1,
    ParametricPlot[{light[Min[T - 1, 1.5], {2, 1}, 1],
      light[Min[T - 1, 3.5], {0, 1}, 1], light[T - 1, {2, 1}, -1],
      light[T - 1, {0, 1}, -1]}, {T, 1 - 10^-3, t},
     PlotStyle -> Directive[Thick, Darker@Blue]]
    , Graphics[]
    ]
   ];
Manipulate[frame[t], {t, 0, 5}]