Using an Item which is forbidden to one's self for the meal, like wine for a Nazirite or Terumah for a non-Kohen: Eruvin 26b, 28a, 30a-b; Pesachim 23a
Using an item which one has sworn not to eat: Eruvin 30a
Using an item from which one has sworn not to benefit: Eruvin 30a
Using sanctified property which has (not) been redeemed: Eruvin 30a, 31a, 31b
Using produce which might not have been tithed yet [Demai]: Eruvin 31a-b
Using produce which has been separated as Maaser Rishon, and which has (not) had the special Terumah tithe [Terumat Maaser] removed from it, if the general Terumah has not been removed from its produce yet: Eruvin 31a, 31b
Using secondary tithe which has [not] been redeemed: Eruvin 31a, 31b
Using the dough tithe: Eruvin 31a, 31b
Using produce which still requires tithing [Tevel], rabbinically: Eruvin 31a, 31b
Determining what constitutes a meal by local custom, vs. global custom: Eruvin 28a
How large the meal must be: Eruvin 82b; Ketuvot 64b
Determining the necessary amount constituting a "meal" based on the significance of the food involved: Eruvin 29a
Determining the size of a meal by the individual's health and appetite: Eruvin 29b-30b
Using water or salt for the meal: Eruvin 26b, 27a-b, 81a; Kiddushin 34a
Using mushrooms for the meal: Eruvin 27a; Kiddushin 34a
Using onions for the meal: Eruvin 29a
Using various types of herbs and grasses for the meal: Eruvin 28a, 28b
Using soft beans for the meal: Eruvin 28b
Using apples for the meal: Eruvin 29a
Using raw beets for the meal: Eruvin 28b-29a
Using raw meat: Eruvin 30a
Using raw eggs: Eruvin 30a
Using unripe dates for the meal: Eruvin 28a, 28b
Using liquor for the meal: Eruvin 29b
The minimum number of dates for the meal: Eruvin 29b
The minimum measure of spices for the meal: Eruvin 29a
The minimum measure of greens for the meal: Eruvin 29a
The minimum number of nuts for the meal: Eruvin 29a
The minimum number of peaches for the meal: Eruvin 29a
The minimum number of pomegranates for the meal: Eruvin 29a
The minimum number of citrons for the meal: Eruvin 29a
The minimum measure of wheat, barley or Kusmin for the meal: Eruvin 29a
The minimum measure of dried figs for the meal: Eruvin 29a
The minimum portion of pressed figs for the meal: Eruvin 29a
The minimum measure of wine or oil for the meal: Eruvin 29a
The minimum measure of vinegar for the meal: Eruvin 29a
The minimum number of olives for the meal: Eruvin 29a
The minimum measure of "Shetita," dried grain mixed with honey: Eruvin 29b
The minimum measure of dried grain: Eruvin 29b
The minimum amount of meat: Eruvin 29b
General rule for sandwich material vs. non-sandwich material: Eruvin 29b-30a
The general rule is that the produce should be enough to provide two meals: Eruvin 29a
Using an herb which is not healthy for most people: Eruvin 28a